diff --git a/build.gradle.kts b/build.gradle.kts
index 7d2c579..2ec2853 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -6,7 +6,7 @@ plugins {
 }
 
 group = "com.mapk"
-version = "0.20"
+version = "0.21"
 
 java {
     sourceCompatibility = JavaVersion.VERSION_1_8
diff --git a/src/main/kotlin/com/mapk/kmapper/BoundParameterForMap.kt b/src/main/kotlin/com/mapk/kmapper/BoundParameterForMap.kt
index e61d775..03d0d96 100644
--- a/src/main/kotlin/com/mapk/kmapper/BoundParameterForMap.kt
+++ b/src/main/kotlin/com/mapk/kmapper/BoundParameterForMap.kt
@@ -21,9 +21,7 @@ internal class BoundParameterForMap<S : Any>(val param: KParameter, property: KP
         val paramClazz = param.type.classifier as KClass<*>
         val propertyClazz = property.returnType.classifier as KClass<*>
 
-        val converter = (convertersFromConstructors(paramClazz) +
-                convertersFromStaticMethods(paramClazz) +
-                convertersFromCompanionObject(paramClazz))
+        val converter = paramClazz.getConverters()
             .filter { (key, _) -> propertyClazz.isSubclassOf(key) }
             .let {
                 if (1 < it.size) throw IllegalArgumentException("${param.name} has multiple converter. $it")
diff --git a/src/main/kotlin/com/mapk/kmapper/KMapper.kt b/src/main/kotlin/com/mapk/kmapper/KMapper.kt
new file mode 100644
index 0000000..dc9461e
--- /dev/null
+++ b/src/main/kotlin/com/mapk/kmapper/KMapper.kt
@@ -0,0 +1,110 @@
+package com.mapk.kmapper
+
+import com.mapk.annotations.KGetterAlias
+import com.mapk.annotations.KGetterIgnore
+import com.mapk.core.ArgumentBucket
+import com.mapk.core.KFunctionForCall
+import com.mapk.core.getAliasOrName
+import com.mapk.core.isUseDefaultArgument
+import com.mapk.core.toKConstructor
+import java.lang.reflect.Method
+import kotlin.reflect.KClass
+import kotlin.reflect.KFunction
+import kotlin.reflect.KParameter
+import kotlin.reflect.KVisibility
+import kotlin.reflect.full.memberProperties
+import kotlin.reflect.jvm.javaGetter
+
+class KMapper<T : Any> private constructor(
+    private val function: KFunctionForCall<T>,
+    parameterNameConverter: (String) -> String
+) {
+    constructor(function: KFunction<T>, parameterNameConverter: (String) -> String = { it }) : this(
+        KFunctionForCall(function), parameterNameConverter
+    )
+
+    constructor(clazz: KClass<T>, parameterNameConverter: (String) -> String = { it }) : this(
+        clazz.toKConstructor(), parameterNameConverter
+    )
+
+    private val parameterMap: Map<String, ParameterForMap<*>> = function.parameters
+        .filter { it.kind != KParameter.Kind.INSTANCE && !it.isUseDefaultArgument() }
+        .associate { (parameterNameConverter(it.getAliasOrName()!!)) to ParameterForMap.newInstance(it) }
+
+    private fun bindArguments(argumentBucket: ArgumentBucket, src: Any) {
+        src::class.memberProperties.forEach outer@{ property ->
+            // propertyが公開されていない場合は処理を行わない
+            if (property.visibility != KVisibility.PUBLIC) return@outer
+
+            // ゲッターが取れない場合は処理を行わない
+            val javaGetter: Method = property.javaGetter ?: return@outer
+
+            var alias: String? = null
+            // NOTE: IgnoreとAliasが同時に指定されるようなパターンを考慮してaliasが取れてもbreakしていない
+            javaGetter.annotations.forEach {
+                if (it is KGetterIgnore) return@outer // ignoreされている場合は処理を行わない
+                if (it is KGetterAlias) alias = it.value
+            }
+
+            parameterMap[alias ?: property.name]?.let {
+                // javaGetterを呼び出す方が高速
+                javaGetter.isAccessible = true
+                argumentBucket.putIfAbsent(it.param, javaGetter.invoke(src)?.let { value -> it.mapObject(value) })
+                // 終了判定
+                if (argumentBucket.isInitialized) return
+            }
+        }
+    }
+
+    private fun bindArguments(argumentBucket: ArgumentBucket, src: Map<*, *>) {
+        src.forEach { (key, value) ->
+            parameterMap[key]?.let { param ->
+                // 取得した内容がnullでなければ適切にmapする
+                argumentBucket.putIfAbsent(param.param, value?.let { param.mapObject(value) })
+                // 終了判定
+                if (argumentBucket.isInitialized) return
+            }
+        }
+    }
+
+    private fun bindArguments(argumentBucket: ArgumentBucket, srcPair: Pair<*, *>) {
+        parameterMap[srcPair.first.toString()]?.let {
+            argumentBucket.putIfAbsent(it.param, srcPair.second?.let { value -> it.mapObject(value) })
+        }
+    }
+
+    fun map(srcMap: Map<String, Any?>): T {
+        val bucket: ArgumentBucket = function.getArgumentBucket()
+        bindArguments(bucket, srcMap)
+
+        return function.call(bucket)
+    }
+
+    fun map(srcPair: Pair<String, Any?>): T {
+        val bucket: ArgumentBucket = function.getArgumentBucket()
+        bindArguments(bucket, srcPair)
+
+        return function.call(bucket)
+    }
+
+    fun map(src: Any): T {
+        val bucket: ArgumentBucket = function.getArgumentBucket()
+        bindArguments(bucket, src)
+
+        return function.call(bucket)
+    }
+
+    fun map(vararg args: Any): T {
+        val bucket: ArgumentBucket = function.getArgumentBucket()
+
+        listOf(*args).forEach { arg ->
+            when (arg) {
+                is Map<*, *> -> bindArguments(bucket, arg)
+                is Pair<*, *> -> bindArguments(bucket, arg)
+                else -> bindArguments(bucket, arg)
+            }
+        }
+
+        return function.call(bucket)
+    }
+}
diff --git a/src/main/kotlin/com/mapk/kmapper/ParameterForMap.kt b/src/main/kotlin/com/mapk/kmapper/ParameterForMap.kt
new file mode 100644
index 0000000..4dd300e
--- /dev/null
+++ b/src/main/kotlin/com/mapk/kmapper/ParameterForMap.kt
@@ -0,0 +1,50 @@
+package com.mapk.kmapper
+
+import com.mapk.core.EnumMapper
+import kotlin.reflect.KClass
+import kotlin.reflect.KFunction
+import kotlin.reflect.KParameter
+import kotlin.reflect.full.isSuperclassOf
+
+internal class ParameterForMap<T : Any> private constructor(val param: KParameter, private val clazz: KClass<T>) {
+    private val javaClazz: Class<T> by lazy {
+        clazz.java
+    }
+    // リストの長さが小さいと期待されるためこの形で実装しているが、理想的にはmap的なものが使いたい
+    private val converters: Set<Pair<KClass<*>, KFunction<T>>> = clazz.getConverters()
+
+    private val convertCache: MutableMap<KClass<*>, (Any) -> Any?> = HashMap()
+
+    fun <U : Any> mapObject(value: U): Any? {
+        val valueClazz: KClass<*> = value::class
+
+        // 取得方法のキャッシュが有ればそれを用いる
+        convertCache[valueClazz]?.let { return it(value) }
+
+        // パラメータに対してvalueが代入可能（同じもしくは親クラス）であればそのまま用いる
+        if (clazz.isSuperclassOf(valueClazz)) {
+            convertCache[valueClazz] = { value }
+            return value
+        }
+
+        val converter: KFunction<*>? = converters.getConverter(valueClazz)
+
+        val lambda: (Any) -> Any? = when {
+            // converterに一致する組み合わせが有れば設定されていればそれを使う
+            converter != null -> { { converter.call(it) } }
+            // 要求された値がenumかつ元が文字列ならenum mapperでマップ
+            javaClazz.isEnum && value is String -> { { EnumMapper.getEnum(javaClazz, it as String) } }
+            // 要求されているパラメータがStringならtoStringする
+            clazz == String::class -> { { it.toString() } }
+            else -> throw IllegalArgumentException("Can not convert $valueClazz to $clazz")
+        }
+        convertCache[valueClazz] = lambda
+        return lambda(value)
+    }
+
+    companion object {
+        fun newInstance(param: KParameter): ParameterForMap<*> {
+            return ParameterForMap(param, param.type.classifier as KClass<*>)
+        }
+    }
+}
diff --git a/src/main/kotlin/com/mapk/kmapper/ParameterUtils.kt b/src/main/kotlin/com/mapk/kmapper/ParameterUtils.kt
index 4e7dcb7..be1e830 100644
--- a/src/main/kotlin/com/mapk/kmapper/ParameterUtils.kt
+++ b/src/main/kotlin/com/mapk/kmapper/ParameterUtils.kt
@@ -6,10 +6,14 @@ import kotlin.reflect.KClass
 import kotlin.reflect.KFunction
 import kotlin.reflect.full.companionObjectInstance
 import kotlin.reflect.full.functions
+import kotlin.reflect.full.isSubclassOf
 import kotlin.reflect.full.staticFunctions
 import kotlin.reflect.jvm.isAccessible
 
-internal fun <T> Collection<KFunction<T>>.getConverterMapFromFunctions(): Set<Pair<KClass<*>, KFunction<T>>> {
+internal fun <T : Any> KClass<T>.getConverters(): Set<Pair<KClass<*>, KFunction<T>>> =
+    convertersFromConstructors(this) + convertersFromStaticMethods(this) + convertersFromCompanionObject(this)
+
+private fun <T> Collection<KFunction<T>>.getConverterMapFromFunctions(): Set<Pair<KClass<*>, KFunction<T>>> {
     return filter { it.annotations.any { annotation -> annotation is KConverter } }
         .map { func ->
             func.isAccessible = true
@@ -18,19 +22,19 @@ internal fun <T> Collection<KFunction<T>>.getConverterMapFromFunctions(): Set<Pa
         }.toSet()
 }
 
-internal fun <T : Any> convertersFromConstructors(clazz: KClass<T>): Set<Pair<KClass<*>, KFunction<T>>> {
+private fun <T : Any> convertersFromConstructors(clazz: KClass<T>): Set<Pair<KClass<*>, KFunction<T>>> {
     return clazz.constructors.getConverterMapFromFunctions()
 }
 
 @Suppress("UNCHECKED_CAST")
-internal fun <T : Any> convertersFromStaticMethods(clazz: KClass<T>): Set<Pair<KClass<*>, KFunction<T>>> {
+private fun <T : Any> convertersFromStaticMethods(clazz: KClass<T>): Set<Pair<KClass<*>, KFunction<T>>> {
     val staticFunctions: Collection<KFunction<T>> = clazz.staticFunctions as Collection<KFunction<T>>
 
     return staticFunctions.getConverterMapFromFunctions()
 }
 
 @Suppress("UNCHECKED_CAST")
-internal fun <T : Any> convertersFromCompanionObject(clazz: KClass<T>): Set<Pair<KClass<*>, KFunction<T>>> {
+private fun <T : Any> convertersFromCompanionObject(clazz: KClass<T>): Set<Pair<KClass<*>, KFunction<T>>> {
     return clazz.companionObjectInstance?.let { companionObject ->
         companionObject::class.functions
             .filter { it.annotations.any { annotation -> annotation is KConverter } }
@@ -44,3 +48,7 @@ internal fun <T : Any> convertersFromCompanionObject(clazz: KClass<T>): Set<Pair
             }.toSet()
     } ?: emptySet()
 }
+
+// 引数の型がconverterに対して入力可能ならconverterを返す
+internal fun <T : Any> Set<Pair<KClass<*>, KFunction<T>>>.getConverter(input: KClass<out T>): KFunction<T>? =
+    this.find { (key, _) -> input.isSubclassOf(key) }?.second
diff --git a/src/main/kotlin/com/mapk/kmapper/PlainParameterForMap.kt b/src/main/kotlin/com/mapk/kmapper/PlainParameterForMap.kt
index 9c95bb3..1c9a880 100644
--- a/src/main/kotlin/com/mapk/kmapper/PlainParameterForMap.kt
+++ b/src/main/kotlin/com/mapk/kmapper/PlainParameterForMap.kt
@@ -4,7 +4,6 @@ import com.mapk.core.EnumMapper
 import kotlin.reflect.KClass
 import kotlin.reflect.KFunction
 import kotlin.reflect.KParameter
-import kotlin.reflect.full.isSubclassOf
 import kotlin.reflect.full.isSuperclassOf
 
 internal class PlainParameterForMap<T : Any> private constructor(val param: KParameter, private val clazz: KClass<T>) {
@@ -12,9 +11,7 @@ internal class PlainParameterForMap<T : Any> private constructor(val param: KPar
         clazz.java
     }
     // リストの長さが小さいと期待されるためこの形で実装しているが、理想的にはmap的なものが使いたい
-    private val converters: Set<Pair<KClass<*>, KFunction<T>>> by lazy {
-        convertersFromConstructors(clazz) + convertersFromStaticMethods(clazz) + convertersFromCompanionObject(clazz)
-    }
+    private val converters: Set<Pair<KClass<*>, KFunction<T>>> = clazz.getConverters()
 
     fun <U : Any> mapObject(value: U): Any? {
         val valueClazz: KClass<*> = value::class
@@ -22,7 +19,7 @@ internal class PlainParameterForMap<T : Any> private constructor(val param: KPar
         // パラメータに対してvalueが代入可能（同じもしくは親クラス）であればそのまま用いる
         if (clazz.isSuperclassOf(valueClazz)) return value
 
-        val converter: KFunction<*>? = getConverter(valueClazz)
+        val converter: KFunction<*>? = converters.getConverter(valueClazz)
 
         return when {
             // converterに一致する組み合わせが有れば設定されていればそれを使う
@@ -35,10 +32,6 @@ internal class PlainParameterForMap<T : Any> private constructor(val param: KPar
         }
     }
 
-    // 引数の型がconverterに対して入力可能ならconverterを返す
-    private fun <R : Any> getConverter(input: KClass<out R>): KFunction<T>? =
-        converters.find { (key, _) -> input.isSubclassOf(key) }?.second
-
     companion object {
         fun newInstance(param: KParameter): PlainParameterForMap<*> {
             return PlainParameterForMap(param, param.type.classifier as KClass<*>)
diff --git a/src/test/kotlin/com/mapk/kmapper/ConverterKMapperTest.kt b/src/test/kotlin/com/mapk/kmapper/ConverterKMapperTest.kt
index c619be7..4f8465e 100644
--- a/src/test/kotlin/com/mapk/kmapper/ConverterKMapperTest.kt
+++ b/src/test/kotlin/com/mapk/kmapper/ConverterKMapperTest.kt
@@ -31,6 +31,37 @@ private data class BoundStaticMethodConverterSrc(val argument: String)
 
 @DisplayName("コンバータ有りでのマッピングテスト")
 class ConverterKMapperTest {
+    @Nested
+    @DisplayName("KMapper")
+    inner class KMapperTest {
+        @Test
+        @DisplayName("コンストラクターでのコンバートテスト")
+        fun constructorConverterTest() {
+            val mapper = KMapper(ConstructorConverterDst::class)
+            val result = mapper.map(mapOf("argument" to 1))
+
+            assertEquals(ConstructorConverter(1), result.argument)
+        }
+
+        @Test
+        @DisplayName("コンパニオンオブジェクトに定義したコンバータでのコンバートテスト")
+        fun companionConverterTest() {
+            val mapper = KMapper(CompanionConverterDst::class)
+            val result = mapper.map(mapOf("argument" to "arg"))
+
+            assertEquals("arg", result.argument.arg)
+        }
+
+        @Test
+        @DisplayName("スタティックメソッドに定義したコンバータでのコンバートテスト")
+        fun staticMethodConverterTest() {
+            val mapper = KMapper(StaticMethodConverterDst::class)
+            val result = mapper.map(mapOf("argument" to "1,2,3"))
+
+            assertTrue(intArrayOf(1, 2, 3) contentEquals result.argument.arg)
+        }
+    }
+
     @Nested
     @DisplayName("PlainKMapper")
     inner class PlainKMapperTest {
diff --git a/src/test/kotlin/com/mapk/kmapper/DefaultArgumentTest.kt b/src/test/kotlin/com/mapk/kmapper/DefaultArgumentTest.kt
index 9720ac1..ae1a1df 100644
--- a/src/test/kotlin/com/mapk/kmapper/DefaultArgumentTest.kt
+++ b/src/test/kotlin/com/mapk/kmapper/DefaultArgumentTest.kt
@@ -13,6 +13,16 @@ class DefaultArgumentTest {
 
     private val src = Src(1, "src")
 
+    @Nested
+    @DisplayName("KMapper")
+    inner class KMapperTest {
+        @Test
+        fun test() {
+            val result = KMapper(::Dst).map(src)
+            assertEquals(Dst(1, "default"), result)
+        }
+    }
+
     @Nested
     @DisplayName("PlainKMapper")
     inner class PlainKMapperTest {
diff --git a/src/test/kotlin/com/mapk/kmapper/EnumMappingTest.kt b/src/test/kotlin/com/mapk/kmapper/EnumMappingTest.kt
index 9515c3f..045d7a2 100644
--- a/src/test/kotlin/com/mapk/kmapper/EnumMappingTest.kt
+++ b/src/test/kotlin/com/mapk/kmapper/EnumMappingTest.kt
@@ -16,6 +16,20 @@ private class EnumMappingDst(val language: JvmLanguage?)
 
 @DisplayName("文字列 -> Enumのマッピングテスト")
 class EnumMappingTest {
+    @Nested
+    @DisplayName("KMapper")
+    inner class KMapperTest {
+        private val mapper = KMapper(EnumMappingDst::class)
+
+        @ParameterizedTest(name = "Non-Null要求")
+        @EnumSource(value = JvmLanguage::class)
+        fun test(language: JvmLanguage) {
+            val result = mapper.map("language" to language.name)
+
+            assertEquals(language, result.language)
+        }
+    }
+
     @Nested
     @DisplayName("PlainKMapper")
     inner class PlainKMapperTest {
diff --git a/src/test/kotlin/com/mapk/kmapper/KGetterIgnoreTest.kt b/src/test/kotlin/com/mapk/kmapper/KGetterIgnoreTest.kt
index a0de4e8..85b68cd 100644
--- a/src/test/kotlin/com/mapk/kmapper/KGetterIgnoreTest.kt
+++ b/src/test/kotlin/com/mapk/kmapper/KGetterIgnoreTest.kt
@@ -13,6 +13,25 @@ class KGetterIgnoreTest {
 
     data class Dst(val arg1: Int, val arg2: String, val arg3: Int, val arg4: String)
 
+    @Nested
+    @DisplayName("KMapper")
+    inner class KMapperTest {
+        @Test
+        @DisplayName("フィールドを無視するテスト")
+        fun test() {
+            val src1 = Src1(1, "2-1", 31)
+            val src2 = Src2("2-2", 32, "4")
+
+            val mapper = KMapper(::Dst)
+
+            val dst1 = mapper.map(src1, src2)
+            val dst2 = mapper.map(src2, src1)
+
+            assertTrue(dst1 == dst2)
+            assertEquals(Dst(1, "2-1", 32, "4"), dst1)
+        }
+    }
+
     @Nested
     @DisplayName("PlainKMapper")
     inner class PlainKMapperTest {
diff --git a/src/test/kotlin/com/mapk/kmapper/ParameterNameConverterTest.kt b/src/test/kotlin/com/mapk/kmapper/ParameterNameConverterTest.kt
index b243ebd..ecac694 100644
--- a/src/test/kotlin/com/mapk/kmapper/ParameterNameConverterTest.kt
+++ b/src/test/kotlin/com/mapk/kmapper/ParameterNameConverterTest.kt
@@ -11,6 +11,24 @@ private data class BoundSrc(val camel_case: String)
 
 @DisplayName("パラメータ名変換のテスト")
 class ParameterNameConverterTest {
+    @Nested
+    @DisplayName("KMapper")
+    inner class KMapperTest {
+        @Test
+        @DisplayName("スネークケースsrc -> キャメルケースdst")
+        fun test() {
+            val expected = "snakeCase"
+            val src = mapOf("camel_case" to expected)
+
+            val mapper = KMapper(CamelCaseDst::class) {
+                CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, it)
+            }
+            val result = mapper.map(src)
+
+            assertEquals(expected, result.camelCase)
+        }
+    }
+
     @Nested
     @DisplayName("PlainKMapper")
     inner class PlainKMapperTest {
diff --git a/src/test/kotlin/com/mapk/kmapper/PropertyAliasTest.kt b/src/test/kotlin/com/mapk/kmapper/PropertyAliasTest.kt
index 23638b7..ec61bfd 100644
--- a/src/test/kotlin/com/mapk/kmapper/PropertyAliasTest.kt
+++ b/src/test/kotlin/com/mapk/kmapper/PropertyAliasTest.kt
@@ -20,6 +20,35 @@ private data class AliasedSrc(
 
 @DisplayName("エイリアスを貼った場合のテスト")
 class PropertyAliasTest {
+    @Nested
+    @DisplayName("KMapper")
+    inner class KMapperTest {
+        @Test
+        @DisplayName("パラメータにエイリアスを貼った場合")
+        fun paramAliasTest() {
+            val src = mapOf(
+                "arg1" to 1.0,
+                "arg2" to "2",
+                "arg3" to 3
+            )
+
+            val result = KMapper(::AliasedDst).map(src)
+
+            assertEquals(1.0, result.arg1)
+            assertEquals(3, result.arg2)
+        }
+
+        @Test
+        @DisplayName("ゲッターにエイリアスを貼った場合")
+        fun getAliasTest() {
+            val src = AliasedSrc(1.0, 2)
+            val result = KMapper(::AliasedDst).map(src)
+
+            assertEquals(1.0, result.arg1)
+            assertEquals(2, result.arg2)
+        }
+    }
+
     @Nested
     @DisplayName("PlainKMapper")
     inner class PlainKMapperTest {
diff --git a/src/test/kotlin/com/mapk/kmapper/SimpleKMapperTest.kt b/src/test/kotlin/com/mapk/kmapper/SimpleKMapperTest.kt
index 12a0169..a26ce59 100644
--- a/src/test/kotlin/com/mapk/kmapper/SimpleKMapperTest.kt
+++ b/src/test/kotlin/com/mapk/kmapper/SimpleKMapperTest.kt
@@ -73,6 +73,96 @@ class SimpleKMapperTest {
         return SimpleDst(arg1, arg2, arg3)
     }
 
+    @Nested
+    @DisplayName("KMapper")
+    inner class KMapperTest {
+        private val mappers: Set<KMapper<out SimpleDst>> = setOf(
+            KMapper(SimpleDst::class),
+            KMapper(::SimpleDst),
+            KMapper((SimpleDst)::factory),
+            KMapper(::instanceFunction),
+            KMapper(SimpleDstExt::class)
+        )
+
+        @Nested
+        @DisplayName("Map<String, Any?>からマップ")
+        inner class FromMap {
+            @Test
+            @DisplayName("Nullを含まない場合")
+            fun testWithoutNull() {
+                val srcMap: Map<String, Any?> = mapOf(
+                    "arg1" to 2,
+                    "arg2" to "value",
+                    "arg3" to 1.0
+                )
+
+                val dsts = mappers.map { it.map(srcMap) }
+
+                assertEquals(1, dsts.distinct().size)
+                dsts.first().let {
+                    assertEquals(2, it.arg1)
+                    assertEquals("value", it.arg2)
+                    assertEquals(1.0, it.arg3)
+                }
+            }
+
+            @Test
+            @DisplayName("Nullを含む場合")
+            fun testContainsNull() {
+                val srcMap: Map<String, Any?> = mapOf(
+                    "arg1" to 1,
+                    "arg2" to null,
+                    "arg3" to 2.0f
+                )
+
+                val dsts = mappers.map { it.map(srcMap) }
+
+                assertEquals(1, dsts.distinct().size)
+                dsts.first().let {
+                    assertEquals(1, it.arg1)
+                    assertEquals(null, it.arg2)
+                    assertEquals(2.0f, it.arg3)
+                }
+            }
+        }
+
+        @Nested
+        @DisplayName("インスタンスからマップ")
+        inner class FromInstance {
+            @Test
+            @DisplayName("Nullを含まない場合")
+            fun testWithoutNull() {
+                val stringValue = "value"
+
+                val src = Src1(stringValue)
+
+                val dsts = mappers.map { it.map(src) }
+
+                assertEquals(1, dsts.distinct().size)
+                dsts.first().let {
+                    assertEquals(stringValue.length, it.arg1)
+                    assertEquals(stringValue, it.arg2)
+                    assertEquals(stringValue.length.toByte(), it.arg3)
+                }
+            }
+
+            @Test
+            @DisplayName("Nullを含む場合")
+            fun testContainsNull() {
+                val src = Src1(null)
+
+                val dsts = mappers.map { it.map(src) }
+
+                assertEquals(1, dsts.distinct().size)
+                dsts.first().let {
+                    assertEquals(0, it.arg1)
+                    assertEquals(null, it.arg2)
+                    assertEquals(0.toByte(), it.arg3)
+                }
+            }
+        }
+    }
+
     @Nested
     @DisplayName("PlainKMapper")
     inner class PlainKMapperTest {
diff --git a/src/test/kotlin/com/mapk/kmapper/StringMappingTest.kt b/src/test/kotlin/com/mapk/kmapper/StringMappingTest.kt
index 0488639..ff42fe2 100644
--- a/src/test/kotlin/com/mapk/kmapper/StringMappingTest.kt
+++ b/src/test/kotlin/com/mapk/kmapper/StringMappingTest.kt
@@ -10,6 +10,16 @@ private data class BoundMappingSrc(val value: Int)
 
 @DisplayName("文字列に対してtoStringしたものを渡すテスト")
 class StringMappingTest {
+    @Nested
+    @DisplayName("KMapper")
+    inner class KMapperTest {
+        @Test
+        fun test() {
+            val result: StringMappingDst = KMapper(StringMappingDst::class).map("value" to 1)
+            assertEquals("1", result.value)
+        }
+    }
+
     @Nested
     @DisplayName("PlainKMapper")
     inner class PlainKMapperTest {