diff --git a/app/build.gradle b/app/build.gradle
index a4d2725..9395665 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -45,6 +45,8 @@ dependencies {
     implementation project(':feature:child')
     implementation project(':feature:setting')
 
+    implementation project(':data')
+
     implementation project(':shared')
     implementation project(':utils')
 
@@ -57,4 +59,8 @@ dependencies {
     implementation libs.navigation.fragment
     implementation libs.navigation.ui
     implementation libs.navigation.dynamic.features.fragment
+
+    // Retrofit
+    implementation libs.retrofit
+    implementation libs.converter.gson
 }
\ No newline at end of file
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 03435ca..b6d3fd6 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -2,7 +2,10 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools">
 
+    <uses-permission android:name="android.permission.INTERNET" />
+
     <application
+        android:name=".KidShiftApplication"
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:fullBackupContent="@xml/backup_rules"
@@ -10,9 +13,11 @@
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
-        android:name=".KidShiftApplication"
         android:theme="@style/Theme.KidShift"
         tools:targetApi="31">
+        <activity
+            android:name=".LoginActivity"
+            android:exported="false" />
         <activity
             android:name=".MainActivity"
             android:exported="true">
diff --git a/app/src/main/java/one/nem/kidshift/LoginActivity.java b/app/src/main/java/one/nem/kidshift/LoginActivity.java
new file mode 100644
index 0000000..d8a5fd7
--- /dev/null
+++ b/app/src/main/java/one/nem/kidshift/LoginActivity.java
@@ -0,0 +1,104 @@
+package one.nem.kidshift;
+
+import android.os.Bundle;
+import android.widget.EditText;
+
+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 java.io.IOException;
+import java.util.concurrent.CompletableFuture;
+
+import javax.inject.Inject;
+
+import dagger.hilt.android.AndroidEntryPoint;
+import one.nem.kidshift.data.UserSettings;
+import one.nem.kidshift.data.retrofit.KidShiftApiService;
+import one.nem.kidshift.data.retrofit.model.parent.auth.ParentLoginRequest;
+import one.nem.kidshift.data.retrofit.model.parent.auth.ParentLoginResponse;
+import one.nem.kidshift.utils.KSLogger;
+import retrofit2.Response;
+import retrofit2.Retrofit;
+import retrofit2.converter.gson.GsonConverterFactory;
+
+@AndroidEntryPoint
+public class LoginActivity extends AppCompatActivity {
+
+    @Inject
+    KSLogger logger;
+
+    @Inject
+    UserSettings userSettings;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        EdgeToEdge.enable(this);
+        setContentView(R.layout.activity_login);
+        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;
+        });
+
+        // Retrofit init
+        KidShiftApiService apiService = new Retrofit.Builder()
+                .baseUrl("https://kidshift-beta.nem.one/")
+                .addConverterFactory(GsonConverterFactory.create())
+                .build()
+                .create(KidShiftApiService.class);
+
+        EditText emailEditText = findViewById(R.id.emailEditText);
+        EditText passwordEditText = findViewById(R.id.passwordEditText);
+
+        findViewById(R.id.loginButton).setOnClickListener(v -> {
+            CompletableFuture.supplyAsync(() -> {
+                try {
+                    Response<ParentLoginResponse> response = apiService.parentLogin(
+                            new ParentLoginRequest(
+                                    emailEditText.getText().toString(),
+                                    passwordEditText.getText().toString()
+                            )).execute();
+
+                    return response;
+                } catch (IOException e) {
+                    logger.error("IOException");
+                    throw new RuntimeException(e);
+                }
+            }).thenAccept(response -> {
+                if (response.isSuccessful()) {
+                    logger.info("Login Success");
+                    logger.debug("AccessToken: " + response.body().getAccessToken());
+
+                    UserSettings.AppCommonSetting appCommonSetting = userSettings.getAppCommonSetting();
+                    appCommonSetting.setLoggedIn(true);
+                    appCommonSetting.setAccessToken(response.body().getAccessToken());
+                    appCommonSetting.setChildMode(false);
+
+                    finish();
+                } else {
+                    logger.error("Login Failed");
+                    try {
+                        logger.debug("Response: " + response.errorBody().string());
+                    } catch (IOException e) {
+                        logger.error("IOException while reading error body");
+                    }
+                    // ログイン失敗時の処理
+                }
+            }).exceptionally(e -> {
+                logger.error("Exception occurred: " + e.getMessage());
+                return null;
+            });
+        });
+
+        // for Debug
+        findViewById(R.id.loginButton).setOnLongClickListener(v -> {
+            // ログイン画面をバイパスしてメイン画面に遷移
+            finish();
+            return true;
+        });
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/one/nem/kidshift/MainActivity.java b/app/src/main/java/one/nem/kidshift/MainActivity.java
index a7c2f4b..bacc373 100644
--- a/app/src/main/java/one/nem/kidshift/MainActivity.java
+++ b/app/src/main/java/one/nem/kidshift/MainActivity.java
@@ -1,5 +1,6 @@
 package one.nem.kidshift;
 
+import android.content.Intent;
 import android.os.Bundle;
 
 import androidx.activity.EdgeToEdge;
@@ -17,6 +18,7 @@ import com.google.android.material.bottomnavigation.BottomNavigationView;
 import javax.inject.Inject;
 
 import dagger.hilt.android.AndroidEntryPoint;
+import one.nem.kidshift.data.UserSettings;
 import one.nem.kidshift.utils.KSLogger;
 
 @AndroidEntryPoint
@@ -25,6 +27,9 @@ public class MainActivity extends AppCompatActivity {
     @Inject
     KSLogger ksLogger;
 
+    @Inject
+    UserSettings userSettings;
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -51,5 +56,15 @@ public class MainActivity extends AppCompatActivity {
         } catch (Exception e) {
             e.printStackTrace();
         }
+
+        // Check logged in
+        if (userSettings.getAppCommonSetting().isLoggedIn()) {
+            ksLogger.info("User is logged in!");
+        } else {
+            ksLogger.info("User is not logged in!");
+
+            Intent intent = new Intent(this, LoginActivity.class);
+            startActivity(intent);
+        }
     }
 }
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_login.xml b/app/src/main/res/layout/activity_login.xml
new file mode 100644
index 0000000..389d6ef
--- /dev/null
+++ b/app/src/main/res/layout/activity_login.xml
@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/main"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".LoginActivity">
+
+    <LinearLayout
+        android:id="@+id/inputContainer"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent">
+
+        <EditText
+            android:id="@+id/emailEditText"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:ems="10"
+            android:inputType="textEmailAddress" />
+
+        <EditText
+            android:id="@+id/passwordEditText"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:ems="10"
+            android:inputType="textPassword" />
+
+    </LinearLayout>
+
+    <TextView
+        android:id="@+id/textView"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="※Loginボタン長押しでBypass"
+        app:layout_constraintBottom_toTopOf="@+id/loginButton"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent" />
+
+    <Button
+        android:id="@+id/loginButton"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="LOGIN"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent" />
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/data/build.gradle b/data/build.gradle
index 931755b..6d247a4 100644
--- a/data/build.gradle
+++ b/data/build.gradle
@@ -43,4 +43,8 @@ dependencies {
 
     implementation project(':model')
     implementation project(':utils')
+
+    // Retrofit
+    implementation libs.retrofit
+    implementation libs.converter.gson
 }
\ No newline at end of file
diff --git a/data/src/main/java/one/nem/kidshift/data/UserSettings.java b/data/src/main/java/one/nem/kidshift/data/UserSettings.java
index 517306f..ea4ed71 100644
--- a/data/src/main/java/one/nem/kidshift/data/UserSettings.java
+++ b/data/src/main/java/one/nem/kidshift/data/UserSettings.java
@@ -1,9 +1,23 @@
 package one.nem.kidshift.data;
 
+import one.nem.kidshift.model.ParentModel;
+
 public interface UserSettings {
 
     ApiSetting getApiSetting();
     TaskSetting getTaskSetting();
+    AppCommonSetting getAppCommonSetting();
+
+    interface AppCommonSetting {
+        boolean isLoggedIn();
+        void setLoggedIn(boolean loggedIn);
+
+        String getAccessToken();
+        void setAccessToken(String token);
+
+        boolean isChildMode();
+        void setChildMode(boolean childMode);
+    }
 
     interface ApiSetting {
         String getApiBaseUrl();
diff --git a/data/src/main/java/one/nem/kidshift/data/impl/UserSettingsDummyImpl.java b/data/src/main/java/one/nem/kidshift/data/impl/UserSettingsDummyImpl.java
index 2386b07..0378730 100644
--- a/data/src/main/java/one/nem/kidshift/data/impl/UserSettingsDummyImpl.java
+++ b/data/src/main/java/one/nem/kidshift/data/impl/UserSettingsDummyImpl.java
@@ -18,6 +18,11 @@ public class UserSettingsDummyImpl implements UserSettings {
         return new TaskSettingImpl();
     }
 
+    @Override
+    public AppCommonSetting getAppCommonSetting() {
+        return null;
+    }
+
     @Override
     public UserSettings.ApiSetting getApiSetting() {
         return new ApiSettingImpl();
diff --git a/data/src/main/java/one/nem/kidshift/data/impl/UserSettingsImpl.java b/data/src/main/java/one/nem/kidshift/data/impl/UserSettingsImpl.java
index a3c6726..4686f15 100644
--- a/data/src/main/java/one/nem/kidshift/data/impl/UserSettingsImpl.java
+++ b/data/src/main/java/one/nem/kidshift/data/impl/UserSettingsImpl.java
@@ -30,6 +30,72 @@ public class UserSettingsImpl implements UserSettings {
         return new TaskSettingImpl();
     }
 
+    @Override
+    public AppCommonSetting getAppCommonSetting() {
+        return new AppCommonSettingImpl();
+    }
+
+    public class AppCommonSettingImpl implements UserSettings.AppCommonSetting {
+
+        transient
+        SharedPrefUtils sharedPrefUtils;
+
+        boolean loggedIn;
+        String accessToken;
+        boolean childMode;
+
+        AppCommonSettingImpl() {
+            sharedPrefUtils = sharedPrefUtilsFactory.create("user_settings");
+            AppCommonSettingImpl appCommonSetting = sharedPrefUtils.getObject("app_common_setting", AppCommonSettingImpl.class);
+            if (appCommonSetting != null) {
+                loggedIn = appCommonSetting.isLoggedIn();
+                accessToken = appCommonSetting.getAccessToken().isEmpty() ? "" : appCommonSetting.getAccessToken();
+                childMode = appCommonSetting.isChildMode();
+            } else {
+                loggedIn = false;
+                accessToken = "";
+                childMode = false;
+            }
+        }
+
+        private void save() {
+            sharedPrefUtils.saveObject("app_common_setting", this);
+        }
+
+        @Override
+        public boolean isLoggedIn() {
+            return loggedIn;
+        }
+
+        @Override
+        public void setLoggedIn(boolean loggedIn) {
+            this.loggedIn = loggedIn;
+            save();
+        }
+
+        @Override
+        public String getAccessToken() {
+            return accessToken;
+        }
+
+        @Override
+        public void setAccessToken(String token) {
+            accessToken = token;
+            save();
+        }
+
+        @Override
+        public boolean isChildMode() {
+            return childMode;
+        }
+
+        @Override
+        public void setChildMode(boolean childMode) {
+            this.childMode = childMode;
+            save();
+        }
+    }
+
     public class ApiSettingImpl implements UserSettings.ApiSetting {
 
         transient
diff --git a/data/src/main/java/one/nem/kidshift/data/retrofit/KidShiftApiService.java b/data/src/main/java/one/nem/kidshift/data/retrofit/KidShiftApiService.java
new file mode 100644
index 0000000..c5c24d9
--- /dev/null
+++ b/data/src/main/java/one/nem/kidshift/data/retrofit/KidShiftApiService.java
@@ -0,0 +1,14 @@
+package one.nem.kidshift.data.retrofit;
+
+import one.nem.kidshift.data.retrofit.model.parent.auth.ParentLoginRequest;
+import one.nem.kidshift.data.retrofit.model.parent.auth.ParentLoginResponse;
+import retrofit2.Call;
+import retrofit2.http.Body;
+import retrofit2.http.POST;
+
+public interface KidShiftApiService {
+
+    @POST("/parent/auth/login")
+    Call<ParentLoginResponse> parentLogin(@Body ParentLoginRequest request);
+
+}
diff --git a/data/src/main/java/one/nem/kidshift/data/retrofit/model/parent/auth/ParentLoginRequest.java b/data/src/main/java/one/nem/kidshift/data/retrofit/model/parent/auth/ParentLoginRequest.java
new file mode 100644
index 0000000..5575d28
--- /dev/null
+++ b/data/src/main/java/one/nem/kidshift/data/retrofit/model/parent/auth/ParentLoginRequest.java
@@ -0,0 +1,27 @@
+package one.nem.kidshift.data.retrofit.model.parent.auth;
+
+public class ParentLoginRequest {
+    private String email;
+    private String password;
+
+    public ParentLoginRequest(String email, String password) {
+        this.email = email;
+        this.password = password;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+}
diff --git a/data/src/main/java/one/nem/kidshift/data/retrofit/model/parent/auth/ParentLoginResponse.java b/data/src/main/java/one/nem/kidshift/data/retrofit/model/parent/auth/ParentLoginResponse.java
new file mode 100644
index 0000000..0df582d
--- /dev/null
+++ b/data/src/main/java/one/nem/kidshift/data/retrofit/model/parent/auth/ParentLoginResponse.java
@@ -0,0 +1,17 @@
+package one.nem.kidshift.data.retrofit.model.parent.auth;
+
+public class ParentLoginResponse {
+    private String accessToken;
+
+    public ParentLoginResponse(String accessToken) {
+        this.accessToken = accessToken;
+    }
+
+    public String getAccessToken() {
+        return accessToken;
+    }
+
+    public void setAccessToken(String accessToken) {
+        this.accessToken = accessToken;
+    }
+}
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 8278c18..932a232 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -9,8 +9,10 @@ material = "1.12.0"
 activity = "1.9.0"
 constraintlayout = "2.1.4"
 nav = "2.7.7"
+retrofit = "2.11.0"
 
 [libraries]
+converter-gson = { module = "com.squareup.retrofit2:converter-gson", version.ref = "retrofit" }
 gson = { module = "com.google.code.gson:gson", version.ref = "gson" }
 junit = { group = "junit", name = "junit", version.ref = "junit" }
 ext-junit = { group = "androidx.test.ext", name = "junit", version.ref = "junitVersion" }
@@ -26,6 +28,7 @@ com-google-dagger-hilt-compiler = { group="com.google.dagger", name="hilt-compil
 navigation-fragment = { group="androidx.navigation", name="navigation-fragment", version.ref="nav"}
 navigation-ui = { group="androidx.navigation", name="navigation-ui", version.ref="nav"}
 navigation-dynamic-features-fragment = { group="androidx.navigation", name="navigation-dynamic-features-fragment", version.ref="nav"}
+retrofit = { module = "com.squareup.retrofit2:retrofit", version.ref = "retrofit" }
 
 [plugins]
 androidApplication = { id = "com.android.application", version.ref = "agp" }