diff --git a/build.gradle.kts b/build.gradle.kts
index 0c252ad..3c12044 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -6,7 +6,7 @@ plugins {
 }
 
 group = "com.mapk"
-version = "0.1"
+version = "0.6"
 
 java {
     sourceCompatibility = JavaVersion.VERSION_1_8
@@ -29,6 +29,8 @@ repositories {
 dependencies {
     implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
     implementation(kotlin("reflect"))
+    // https://mvnrepository.com/artifact/org.jetbrains/annotations
+    implementation(group = "org.jetbrains", name = "annotations", version = "19.0.0")
 
     // https://mvnrepository.com/artifact/org.junit.jupiter/junit-jupiter
     testImplementation(group = "org.junit.jupiter", name = "junit-jupiter", version = "5.6.0") {
diff --git a/src/main/java/com/mapk/core/BucketGenerator.java b/src/main/java/com/mapk/core/BucketGenerator.java
index b74eda7..0e909d5 100644
--- a/src/main/java/com/mapk/core/BucketGenerator.java
+++ b/src/main/java/com/mapk/core/BucketGenerator.java
@@ -2,19 +2,24 @@
 
 import kotlin.Pair;
 import kotlin.reflect.KParameter;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
 
 class BucketGenerator {
     private final int initializationStatus;
+    @NotNull
     private final List<Integer> initializeMask;
     private final int completionValue;
 
+    @NotNull
     private final KParameter[] keyArray;
+    @NotNull
     private final Object[] valueArray;
 
-    BucketGenerator(int capacity, Pair<KParameter, Object> instancePair) {
+    BucketGenerator(int capacity, @Nullable Pair<KParameter, Object> instancePair) {
         keyArray = new KParameter[capacity];
         valueArray = new Object[capacity];
 
@@ -38,6 +43,7 @@ class BucketGenerator {
         this.completionValue = completionValue;
     }
 
+    @NotNull
     ArgumentBucket generate() {
         return new ArgumentBucket(
                 keyArray.clone(),
diff --git a/src/main/java/com/mapk/core/EnumMapper.java b/src/main/java/com/mapk/core/EnumMapper.java
index d5074ad..e206016 100644
--- a/src/main/java/com/mapk/core/EnumMapper.java
+++ b/src/main/java/com/mapk/core/EnumMapper.java
@@ -1,5 +1,8 @@
 package com.mapk.core;
 
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
 public class EnumMapper {
     /**
      * Kotlinの型推論バグでクラスからvalueOfが使えないため、ここだけJavaで書いている（型引数もT extends Enumでは書けなかった）
@@ -8,8 +11,9 @@ public class EnumMapper {
      * @param <T> enumClass
      * @return Enum.valueOf
      */
+    @Nullable
     @SuppressWarnings({"unchecked", "rawtypes"})
-    public static <T> T getEnum(Class<T> clazz, String value) {
+    public static <T> T getEnum(@NotNull Class<T> clazz, @Nullable String value) {
         if (value == null || value.isEmpty()) {
             return null;
         }
diff --git a/src/main/kotlin/com/mapk/annotations/KConverter.kt b/src/main/kotlin/com/mapk/annotations/KConstructor.kt
similarity index 83%
rename from src/main/kotlin/com/mapk/annotations/KConverter.kt
rename to src/main/kotlin/com/mapk/annotations/KConstructor.kt
index 35034f7..6ea3720 100644
--- a/src/main/kotlin/com/mapk/annotations/KConverter.kt
+++ b/src/main/kotlin/com/mapk/annotations/KConstructor.kt
@@ -3,4 +3,4 @@ package com.mapk.annotations
 @Target(AnnotationTarget.CONSTRUCTOR, AnnotationTarget.FUNCTION)
 @Retention(AnnotationRetention.RUNTIME)
 @MustBeDocumented
-annotation class KConverter
+annotation class KConstructor
diff --git a/src/main/kotlin/com/mapk/core/ArgumentBucket.kt b/src/main/kotlin/com/mapk/core/ArgumentBucket.kt
index d148cff..266812d 100644
--- a/src/main/kotlin/com/mapk/core/ArgumentBucket.kt
+++ b/src/main/kotlin/com/mapk/core/ArgumentBucket.kt
@@ -1,5 +1,6 @@
 package com.mapk.core
 
+import java.util.Objects
 import kotlin.reflect.KParameter
 
 class ArgumentBucket internal constructor(
@@ -26,9 +27,7 @@ class ArgumentBucket internal constructor(
         return keyArray[key.index] != null
     }
 
-    override fun containsValue(value: Any?): Boolean {
-        throw UnsupportedOperationException()
-    }
+    override fun containsValue(value: Any?): Boolean = valueArray.any { Objects.equals(value, it) }
 
     override fun get(key: KParameter): Any? = valueArray[key.index]
     fun getByIndex(key: Int): Any? =
@@ -42,7 +41,7 @@ class ArgumentBucket internal constructor(
     override val keys: MutableSet<KParameter>
         get() = keyArray.filterNotNull().toMutableSet()
     override val values: MutableCollection<Any?>
-        get() = throw UnsupportedOperationException()
+        get() = valueArray.filterIndexed { i, _ -> initializationStatus and initializeMask[i] != 0 }.toMutableList()
 
     fun putIfAbsent(key: KParameter, value: Any?) {
         val index = key.index
diff --git a/src/main/kotlin/com/mapk/core/Functions.kt b/src/main/kotlin/com/mapk/core/Functions.kt
new file mode 100644
index 0000000..ef29771
--- /dev/null
+++ b/src/main/kotlin/com/mapk/core/Functions.kt
@@ -0,0 +1,10 @@
+package com.mapk.core
+
+import com.mapk.annotations.KParameterAlias
+import kotlin.reflect.KParameter
+import kotlin.reflect.full.findAnnotation
+
+/**
+ * パラメータからエイリアスもしくはプロパティ名を取得する関数
+ */
+fun KParameter.getAliasOrName(): String? = findAnnotation<KParameterAlias>()?.value ?: name
diff --git a/src/main/kotlin/com/mapk/core/KFunctionForCall.kt b/src/main/kotlin/com/mapk/core/KFunctionForCall.kt
index 33b8a3f..51fa697 100644
--- a/src/main/kotlin/com/mapk/core/KFunctionForCall.kt
+++ b/src/main/kotlin/com/mapk/core/KFunctionForCall.kt
@@ -1,10 +1,15 @@
 package com.mapk.core
 
+import com.mapk.annotations.KConstructor
+import kotlin.reflect.KClass
 import kotlin.reflect.KFunction
 import kotlin.reflect.KParameter
+import kotlin.reflect.full.companionObjectInstance
+import kotlin.reflect.full.functions
+import kotlin.reflect.full.primaryConstructor
 import kotlin.reflect.jvm.isAccessible
 
-class KFunctionForCall<T>(private val function: KFunction<T>, instance: Any? = null) {
+class KFunctionForCall<T>(internal val function: KFunction<T>, instance: Any? = null) {
     val parameters: List<KParameter> = function.parameters
     private val generator: BucketGenerator
 
@@ -28,3 +33,23 @@ class KFunctionForCall<T>(private val function: KFunction<T>, instance: Any? = n
         if (argumentBucket.isInitialized) function.call(*argumentBucket.valueArray)
         else function.callBy(argumentBucket)
 }
+
+@Suppress("UNCHECKED_CAST")
+fun <T : Any> KClass<T>.toKConstructor(): KFunctionForCall<T> {
+    val factoryConstructor: List<KFunctionForCall<T>> =
+        this.companionObjectInstance?.let { companionObject ->
+            companionObject::class.functions
+                .filter { it.annotations.any { annotation -> annotation is KConstructor } }
+                .map { KFunctionForCall(it, companionObject) as KFunctionForCall<T> }
+        } ?: emptyList()
+
+    val constructors: List<KFunctionForCall<T>> = factoryConstructor + this.constructors
+        .filter { it.annotations.any { annotation -> annotation is KConstructor } }
+        .map { KFunctionForCall(it) }
+
+    if (constructors.size == 1) return constructors.single()
+
+    if (constructors.isEmpty()) return KFunctionForCall(this.primaryConstructor!!)
+
+    throw IllegalArgumentException("Find multiple target.")
+}
diff --git a/src/test/kotlin/com/mapk/core/ToKConstructorTest.kt b/src/test/kotlin/com/mapk/core/ToKConstructorTest.kt
new file mode 100644
index 0000000..375633d
--- /dev/null
+++ b/src/test/kotlin/com/mapk/core/ToKConstructorTest.kt
@@ -0,0 +1,68 @@
+package com.mapk.core
+
+import com.mapk.annotations.KConstructor
+import kotlin.reflect.KFunction
+import kotlin.reflect.full.memberProperties
+import kotlin.reflect.full.primaryConstructor
+import kotlin.reflect.jvm.isAccessible
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+
+@Suppress("UNCHECKED_CAST", "unused")
+@DisplayName("クラスからのコンストラクタ抽出関連テスト")
+class ToKConstructorTest {
+    private class SecondaryConstructorDst(val argument: Int) {
+        @KConstructor
+        constructor(argument: Number) : this(argument.toInt())
+    }
+
+    class CompanionFactoryDst(val argument: IntArray) {
+        companion object {
+            @KConstructor
+            fun factory(csv: String): CompanionFactoryDst {
+                return csv.split(",").map { it.toInt() }.toIntArray().let { CompanionFactoryDst(it) }
+            }
+        }
+    }
+    private class ConstructorDst(val argument: String)
+    class MultipleConstructorDst @KConstructor constructor(val argument: Int) {
+        @KConstructor
+        constructor(argument: String) : this(argument.toInt())
+    }
+
+    private fun <T : Any> KFunctionForCall<T>.getTargetFunction(): KFunction<T> {
+        return this::class.memberProperties.first { it.name == "function" }.getter.let {
+            it.isAccessible = true
+            it.call(this) as KFunction<T>
+        }
+    }
+
+    @Test
+    @DisplayName("セカンダリコンストラクタからの取得テスト")
+    fun testGetFromSecondaryConstructor() {
+        val function = SecondaryConstructorDst::class.toKConstructor().function
+        Assertions.assertTrue(function.annotations.any { it is KConstructor })
+    }
+
+    @Test
+    @DisplayName("ファクトリーメソッドからの取得テスト")
+    fun testGetFromFactoryMethod() {
+        val function = CompanionFactoryDst::class.toKConstructor().function
+        Assertions.assertTrue(function.annotations.any { it is KConstructor })
+    }
+
+    @Test
+    @DisplayName("無指定でプライマリコンストラクタからの取得テスト")
+    fun testGetFromPrimaryConstructor() {
+        val function = ConstructorDst::class.toKConstructor().function
+        Assertions.assertEquals(ConstructorDst::class.primaryConstructor, function)
+    }
+
+    @Test
+    @DisplayName("対象を複数指定した場合のテスト")
+    fun testMultipleDeclareConstructor() {
+        assertThrows<IllegalArgumentException> { MultipleConstructorDst::class.toKConstructor() }
+    }
+}