diff --git a/data/src/main/java/one/nem/lacerta/source/pref/repository/Common.java b/data/src/main/java/one/nem/lacerta/source/pref/repository/Common.java
index 357671fb..3fb0f187 100644
--- a/data/src/main/java/one/nem/lacerta/source/pref/repository/Common.java
+++ b/data/src/main/java/one/nem/lacerta/source/pref/repository/Common.java
@@ -1,5 +1,17 @@
 package one.nem.lacerta.source.pref.repository;
 
+import java.util.List;
+
 public interface Common {
     // さまざまな用途で使うPref
+
+    String getStringValue(String key);
+
+    void setStringValue(String key, String value);
+
+    boolean isExist(String key);
+
+    void remove(String key);
+
+    List<String> getExistKeys();
 }