diff --git a/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/Birthmarks.java b/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/Birthmarks.java
index eb5be535..57abbd2c 100644
--- a/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/Birthmarks.java
+++ b/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/Birthmarks.java
@@ -4,6 +4,8 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import io.vavr.control.Either;
@@ -24,6 +26,10 @@ public Birthmarks(Stream<Either<Exception, Birthmark<T>>> stream) {
         stream.forEach(either -> either.bimap(t -> exceptions.add(t), r -> list.add(r)));
     }
 
+    public Optional<Birthmark<T>> unify() {
+        return BirthmarksMerger.unifyTo(this);
+    }
+
     public Stream<Birthmark<T>> find(ClassName name) {
         return list.stream()
                 .filter(birthmark -> birthmark.isSame(name));
diff --git a/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/BirthmarksMerger.java b/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/BirthmarksMerger.java
new file mode 100644
index 00000000..cc25ca48
--- /dev/null
+++ b/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/BirthmarksMerger.java
@@ -0,0 +1,61 @@
+package jp.cafebabe.birthmarks.entities;
+
+import io.vavr.control.Try;
+import jp.cafebabe.birthmarks.utils.LongestCommonSubstring;
+import jp.cafebabe.kunai.entries.ClassName;
+
+import java.net.URI;
+import java.nio.file.Path;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+class BirthmarksMerger {
+    public <T> Optional<Birthmark<T>> unify(Birthmarks<T> birthmarks) {
+        Optional<Elements<T>> elements = mergeElements(birthmarks);
+        Metadata metadata = mergeMetadata(birthmarks);
+        return elements.map(e -> new Birthmark<>(metadata, e));
+    }
+
+    private <T> Metadata mergeMetadata(Birthmarks<T> birthmarks) {
+        String location = findCommonLocation(birthmarks.stream());
+        return constructMetadata(location, findType(birthmarks));
+    }
+
+    private <T> Optional<BirthmarkType> findType(Birthmarks<T> birthmarks) {
+        return birthmarks.stream().map(b -> b.type())
+                .collect(Collectors.reducing((a, b) -> a));
+    }
+
+    private Metadata constructMetadata(String location, Optional<BirthmarkType> type) {
+        Try<URI> tryUri = Try.of(() -> new URI(location));
+        Optional<URI> uri = tryUri.toJavaOptional();
+        Optional<ClassName> name = uri.map(u -> new ClassName(findBaseName(u)));
+        return new Metadata(name.orElseGet(() -> new ClassName("<merged>")), uri.get(), type.get());
+    }
+
+    private String findBaseName(URI uri) {
+        String path = uri.toString();
+        int index = path.lastIndexOf('/');
+        if(index >= 0)
+            return path.substring(index + 1);
+        return path;
+    }
+
+    private <T> String findCommonLocation(Stream<Birthmark<T>> stream) {
+        Optional<String> location = stream.map(birthmark -> birthmark.metadata())
+                .map(m -> m.location().toString())
+                .collect(Collectors.reducing((s1, s2) -> LongestCommonSubstring.of(s1, s2)));
+        return location.orElseGet(() -> "");
+    }
+
+    private <T> Optional<Elements<T>> mergeElements(Birthmarks<T> birthmarks) {
+        return birthmarks.stream()
+                .map(birthmark -> birthmark.elements())
+                .collect(Collectors.reducing((a, b) -> a.merge(b)));
+    }
+
+    public static <T> Optional<Birthmark<T>> unifyTo(Birthmarks<T> birthmarks) {
+        return new BirthmarksMerger().unify(birthmarks);
+    }
+}
diff --git a/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/Couple.java b/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/Couple.java
index 278cd52a..45042590 100644
--- a/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/Couple.java
+++ b/pochi-api/src/main/java/jp/cafebabe/birthmarks/entities/Couple.java
@@ -16,6 +16,11 @@ protected Couple(L left, R right) {
         this.right = Objects.requireNonNull(right);
     }
 
+    public void applyIf(BiPredicate<L, R> predicate, BiConsumer<L, R> consumer) {
+        if(predicate.test(left, right))
+            consumer.accept(left, right);
+    }
+
     public L left() {
         return left;
     }
diff --git a/pochi-api/src/main/java/jp/cafebabe/birthmarks/utils/LongestCommonSubstring.java b/pochi-api/src/main/java/jp/cafebabe/birthmarks/utils/LongestCommonSubstring.java
new file mode 100644
index 00000000..881b0c12
--- /dev/null
+++ b/pochi-api/src/main/java/jp/cafebabe/birthmarks/utils/LongestCommonSubstring.java
@@ -0,0 +1,47 @@
+package jp.cafebabe.birthmarks.utils;
+
+import jp.cafebabe.birthmarks.entities.Couple;
+
+import java.util.Optional;
+
+public class LongestCommonSubstring {
+    public static final String of(String s1, String s2) {
+        return new LongestCommonSubstring()
+                .calculate(s1, s2);
+    }
+
+    private String calculate(String s1, String s2) {
+        int[][] table = new int[s1.length() + 1][s2.length() + 1];
+        Result r = Result.of(0, 0, 0);
+        for(int i = 0; i < table.length; i++) {
+            for(int j = 0; j < table[i].length; j++) {
+                if(i == 0 || j == 0) table[i][j] = 0;
+                else if(s1.charAt(i - 1) == s2.charAt(j - 1)) {
+                    table[i][j] = 1 + table[i - 1][j - 1];
+                    r = updateResultIfNeeded(r, i, j, table[i][j]);
+                }
+                // printTable(table);
+            }
+        }
+        return s1.substring(r.i - r.max, r.i);
+    }
+
+    private Result updateResultIfNeeded(Result r, int i, int j, int v) {
+        if(r.max > v)
+            return r;
+        return Result.of(i, j, v);
+    }
+
+    private static final class Result {
+        private int i, j;
+        private int max;
+        private Result(int i, int j, int max) {
+            this.i = i;
+            this.j = j;
+            this.max = max;
+        }
+        public static Result of(int i, int j, int max) {
+            return new Result(i, j, max);
+        }
+    }
+}
diff --git a/pochi-api/src/main/java/module-info.java b/pochi-api/src/main/java/module-info.java
index 30cf358c..8e046bf6 100644
--- a/pochi-api/src/main/java/module-info.java
+++ b/pochi-api/src/main/java/module-info.java
@@ -60,8 +60,9 @@
    exports jp.cafebabe.birthmarks.entities.elements;
    exports jp.cafebabe.birthmarks.extractors;
    exports jp.cafebabe.birthmarks.pairs;
+    exports jp.cafebabe.birthmarks.utils;
 
-   uses jp.cafebabe.birthmarks.comparators.ComparatorBuilder;
+    uses jp.cafebabe.birthmarks.comparators.ComparatorBuilder;
    uses jp.cafebabe.birthmarks.extractors.ExtractorBuilder;
    uses jp.cafebabe.birthmarks.pairs.PairMatcherBuilder;
 }
diff --git a/pochi-api/src/test/java/jp/cafebabe/birthmarks/entities/BirthmarksTest.java b/pochi-api/src/test/java/jp/cafebabe/birthmarks/entities/BirthmarksTest.java
index 0211a8b1..cda35b8e 100644
--- a/pochi-api/src/test/java/jp/cafebabe/birthmarks/entities/BirthmarksTest.java
+++ b/pochi-api/src/test/java/jp/cafebabe/birthmarks/entities/BirthmarksTest.java
@@ -7,6 +7,7 @@
 import java.net.URI;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
@@ -68,4 +69,16 @@ public void testAppend() throws Exception{
         assertThat(list.get(2).metadata().toString(), is("c3,source3,hoge1"));
         assertThat(list.get(3).metadata().toString(), is("o1,otherSource,hoge1"));
     }
+
+    @Test
+    public void testUnify() throws Exception {
+        Optional<Birthmark<String>> optionalResult = birthmarks.unify();
+        if(optionalResult.isEmpty())
+            throw new InternalError();
+        Birthmark<String> result = optionalResult.get();
+        Elements<String> elements = result.elements();
+
+        assertThat(result.className(), is(new ClassName("source")));
+        assertThat(elements.size(), is(9));
+    }
 }
diff --git a/pochi-api/src/test/java/jp/cafebabe/birthmarks/utils/LongestCommonSubstringTest.java b/pochi-api/src/test/java/jp/cafebabe/birthmarks/utils/LongestCommonSubstringTest.java
new file mode 100644
index 00000000..ad68372e
--- /dev/null
+++ b/pochi-api/src/test/java/jp/cafebabe/birthmarks/utils/LongestCommonSubstringTest.java
@@ -0,0 +1,15 @@
+package jp.cafebabe.birthmarks.utils;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+import org.junit.Test;
+
+public class LongestCommonSubstringTest {
+    @Test
+    public void basicTest() {
+        assertThat(LongestCommonSubstring.of("abcdxyz", "xyzabcd"), is("abcd"));
+        assertThat(LongestCommonSubstring.of("abracadabra", "open sesame"), is("a"));
+        assertThat(LongestCommonSubstring.of("aaaa", "bbb"), is(""));
+    }
+}