diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 2791464..17e4369 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -41,8 +41,9 @@
     implementation(libs.constraintlayout)
     implementation(libs.legacy.support.v4)
     implementation(libs.recyclerview)
+    implementation(libs.retrofit2.retrofit)
+    implementation(libs.converter.jackson)
     testImplementation(libs.junit)
     androidTestImplementation(libs.ext.junit)
     androidTestImplementation(libs.espresso.core)
-    implementation(libs.retrofit)
 }
\ No newline at end of file
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index aa8e72b..041ace3 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -31,7 +31,7 @@
             </intent-filter>
         </activity>
         <activity
-            android:name=".MainActivity"
+            android:name=".views.MainActivity"
             android:exported="true" />
     </application>
 
diff --git a/app/src/main/java/com/example/tampopo_client/MainActivity.java b/app/src/main/java/com/example/tampopo_client/MainActivity.java
deleted file mode 100644
index 8700a7e..0000000
--- a/app/src/main/java/com/example/tampopo_client/MainActivity.java
+++ /dev/null
@@ -1,24 +0,0 @@
-package com.example.tampopo_client;
-
-import android.os.Bundle;
-
-import androidx.activity.EdgeToEdge;
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.core.graphics.Insets;
-import androidx.core.view.ViewCompat;
-import androidx.core.view.WindowInsetsCompat;
-
-public class MainActivity extends AppCompatActivity {
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        EdgeToEdge.enable(this);
-        setContentView(R.layout.activity_main);
-        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
-            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
-            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
-            return insets;
-        });
-    }
-}
\ No newline at end of file
diff --git a/app/src/main/java/com/example/tampopo_client/models/FriendPair.java b/app/src/main/java/com/example/tampopo_client/models/FriendPair.java
new file mode 100644
index 0000000..4f9c35f
--- /dev/null
+++ b/app/src/main/java/com/example/tampopo_client/models/FriendPair.java
@@ -0,0 +1,36 @@
+package com.example.tampopo_client.models;
+
+public class FriendPair {
+    private Integer id;
+    private String user0Id;
+    private String user1Id;
+
+    public FriendPair(String user0Id, String user1Id) {
+        this.user0Id = user0Id;
+        this.user1Id = user1Id;
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getUser0Id() {
+        return user0Id;
+    }
+
+    public void setUser0Id(String user0Id) {
+        this.user0Id = user0Id;
+    }
+
+    public String getUser1Id() {
+        return user1Id;
+    }
+
+    public void setUser1Id(String user1Id) {
+        this.user1Id = user1Id;
+    }
+}
diff --git a/app/src/main/java/com/example/tampopo_client/resources/FriendsResource.java b/app/src/main/java/com/example/tampopo_client/resources/FriendsResource.java
new file mode 100644
index 0000000..c390536
--- /dev/null
+++ b/app/src/main/java/com/example/tampopo_client/resources/FriendsResource.java
@@ -0,0 +1,34 @@
+package com.example.tampopo_client.resources;
+
+import com.example.tampopo_client.models.FriendPair;
+
+import retrofit2.Call;
+import retrofit2.http.DELETE;
+import retrofit2.http.Field;
+import retrofit2.http.FormUrlEncoded;
+import retrofit2.http.GET;
+import retrofit2.http.POST;
+import retrofit2.http.Path;
+import retrofit2.http.Query;
+
+public interface FriendsResource {
+    @FormUrlEncoded
+    @POST("friends")
+    Call<FriendPair> postFriends(
+            @Field("token") String token,
+            @Field("user0-id") String user0Id,
+            @Field("user1-id") String user1Id
+    );
+
+    @GET("friends/{pair_id}/")
+    Call<FriendPair> getFriend(
+            @Query("token") String token,
+            @Path("pair_id") String pairId
+    );
+
+    @DELETE("friends/{pair_id}/")
+    void deleteFriend(
+            @Query("token") String token,
+            @Path("pair_id") String pair_id
+    );
+}
diff --git a/app/src/main/java/com/example/tampopo_client/viewmodels/FriendViewModel.java b/app/src/main/java/com/example/tampopo_client/viewmodels/FriendViewModel.java
new file mode 100644
index 0000000..b85f756
--- /dev/null
+++ b/app/src/main/java/com/example/tampopo_client/viewmodels/FriendViewModel.java
@@ -0,0 +1,22 @@
+package com.example.tampopo_client.viewmodels;
+
+import androidx.lifecycle.ViewModel;
+
+import com.example.tampopo_client.resources.FriendsResource;
+
+import retrofit2.Retrofit;
+import retrofit2.converter.jackson.JacksonConverterFactory;
+
+public class FriendViewModel extends ViewModel {
+
+    private final Retrofit retrofit;
+    private final FriendsResource friendsResource;
+
+    public FriendViewModel(){
+        this.retrofit = new Retrofit.Builder()
+                .baseUrl("http://nitta-lab-www.is.konan-u.ac.jp/tampopo-server/")
+                .addConverterFactory(JacksonConverterFactory.create())
+                .build();
+        this.friendsResource = retrofit.create(FriendsResource.class);
+    }
+}
diff --git a/app/src/main/java/com/example/tampopo_client/views/MainActivity.java b/app/src/main/java/com/example/tampopo_client/views/MainActivity.java
new file mode 100644
index 0000000..e9a31b3
--- /dev/null
+++ b/app/src/main/java/com/example/tampopo_client/views/MainActivity.java
@@ -0,0 +1,26 @@
+package com.example.tampopo_client.views;
+
+import android.os.Bundle;
+
+import androidx.activity.EdgeToEdge;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.graphics.Insets;
+import androidx.core.view.ViewCompat;
+import androidx.core.view.WindowInsetsCompat;
+
+import com.example.tampopo_client.R;
+
+public class MainActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        EdgeToEdge.enable(this);
+        setContentView(R.layout.activity_main);
+        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
+            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
+            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
+            return insets;
+        });
+    }
+}
\ No newline at end of file
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index cbc4758..7db8943 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -10,6 +10,8 @@
 legacySupportV4 = "1.0.0"
 recyclerview = "1.3.2"
 retrofit = "3.1.0-SNAPSHOT"
+retrofitVersion = "3.0.0"
+converterJackson = "3.0.0"
 
 [libraries]
 junit = { group = "junit", name = "junit", version.ref = "junit" }
@@ -22,6 +24,8 @@
 legacy-support-v4 = { group = "androidx.legacy", name = "legacy-support-v4", version.ref = "legacySupportV4" }
 recyclerview = { group = "androidx.recyclerview", name = "recyclerview", version.ref = "recyclerview" }
 retrofit = { module = "com.squareup.retrofit2:retrofit", version.ref = "retrofit" }
+retrofit2-retrofit = { group = "com.squareup.retrofit2", name = "retrofit", version.ref = "retrofitVersion" }
+converter-jackson = { group = "com.squareup.retrofit2", name = "converter-jackson", version.ref = "converterJackson" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }