diff --git a/app/src/main/java/com/example/citrusclient/viewmodels/TodoViewModel.java b/app/src/main/java/com/example/citrusclient/viewmodels/TodoViewModel.java
deleted file mode 100644
index 41deb9e..0000000
--- a/app/src/main/java/com/example/citrusclient/viewmodels/TodoViewModel.java
+++ /dev/null
@@ -1,6 +0,0 @@
-package com.example.citrusclient.viewmodels;
-
-import androidx.lifecycle.ViewModel;
-
-public class TodoViewModel extends ViewModel {
-}
diff --git a/app/src/main/java/com/example/citrusclient/viewmodels/TodosViewModel.java b/app/src/main/java/com/example/citrusclient/viewmodels/TodosViewModel.java
new file mode 100644
index 0000000..722398e
--- /dev/null
+++ b/app/src/main/java/com/example/citrusclient/viewmodels/TodosViewModel.java
@@ -0,0 +1,229 @@
+package com.example.citrusclient.viewmodels;
+
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.ViewModel;
+
+import com.example.citrusclient.models.Todo;
+import com.example.citrusclient.models.Book;
+import com.example.citrusclient.rest.TodosRest;
+
+
+import java.util.ArrayList;
+import java.util.HashMap;
+
+import retrofit2.Call;
+import retrofit2.Callback;
+import retrofit2.Response;
+import retrofit2.Retrofit;
+import retrofit2.converter.jackson.JacksonConverterFactory;
+
+public class TodosViewModel extends ViewModel {
+    private final Retrofit retrofit;
+    private final TodosRest todosRest;
+
+    //LiveData
+    private final MutableLiveData<HashMap<Integer, HashMap<Integer, HashMap<Integer, HashMap<Integer, Todo>>>>> allTodosLiveData;
+    private final MutableLiveData<HashMap<Integer, HashMap<Integer, Todo>>> TodosByMonthLiveData;
+    private final MutableLiveData<HashMap<Integer, Todo>> TodosByDayLiveData;
+    private final MutableLiveData<Todo> TodoByIdLiveData;
+    private final MutableLiveData<String> errorLiveData;
+
+    //Constructor
+    public TodosViewModel()
+    {
+        this.retrofit = new Retrofit.Builder()
+                .baseUrl("http://nitta-lab-www.is.konan-u.ac.jp/citrus/")
+                .addConverterFactory(JacksonConverterFactory.create())
+                .build();
+        this.todosRest = retrofit.create(TodosRest.class);
+        this.allTodosLiveData = new MutableLiveData<>();
+        this.TodosByMonthLiveData = new MutableLiveData<>();
+        this.TodosByDayLiveData = new MutableLiveData<>();
+        this.TodoByIdLiveData = new MutableLiveData<>();
+        this.errorLiveData = new MutableLiveData<>();
+    }
+
+    //getter
+    public MutableLiveData<HashMap<Integer, HashMap<Integer, HashMap<Integer, HashMap<Integer, Todo>>>>> getTodosLiveData()
+    {
+        return allTodosLiveData;
+    }
+    public MutableLiveData<String> getErrorLiveData() {return errorLiveData;}
+
+
+    public void getAllTodos(String accountId,Integer bookId, String token)
+    {
+        Call<HashMap<Integer, HashMap<Integer, HashMap<Integer, HashMap<Integer, Todo>>>>> call = todosRest.getAllTodos(accountId, bookId, token);
+        call.enqueue(new Callback<HashMap<Integer, HashMap<Integer, HashMap<Integer, HashMap<Integer, Todo>>>>>() {
+            @Override
+            public void onResponse(Call<HashMap<Integer, HashMap<Integer, HashMap<Integer, HashMap<Integer, Todo>>>>> call, Response<HashMap<Integer, HashMap<Integer, HashMap<Integer, HashMap<Integer, Todo>>>>> response) {
+                if (response.isSuccessful()) {
+                    System.out.println("Success: getAllTodos");
+                    allTodosLiveData.setValue(response.body());
+                } else {
+                    System.out.println("Error: getAllTodos" + response.code());
+                    errorLiveData.setValue(parseStatusCode(response.code()));
+                }
+            }
+            @Override
+            public void onFailure(Call<HashMap<Integer, HashMap<Integer, HashMap<Integer, HashMap<Integer, Todo>>>>> call, Throwable t) {
+                System.out.println("CommunicationError: getAllTodos" + t);
+                errorLiveData.setValue(parseStatusCode(-1));
+            }
+
+        });
+    }
+
+    public void getTodosByMonth(String accountId,Integer bookId, Integer year, Integer month,
+                                String token)
+    {
+        Call<HashMap<Integer, HashMap<Integer, Todo>>> call = todosRest.getTodosByMonth(accountId, bookId, year, month, token);
+        call.enqueue(new Callback<HashMap<Integer, HashMap<Integer, Todo>>>() {
+            @Override
+            public void onResponse(Call<HashMap<Integer, HashMap<Integer, Todo>>> call, Response<HashMap<Integer, HashMap<Integer, Todo>>> response) {
+                if (response.isSuccessful()) {
+                    System.out.println("Success: getTodosByMonth");
+                    TodosByMonthLiveData.setValue(response.body());
+                } else {
+                    System.out.println("Error: getTodosByMonth" + response.code());
+                }
+            }
+            @Override
+            public void onFailure(Call<HashMap<Integer, HashMap<Integer, Todo>>> call, Throwable t) {
+                System.out.println("CommunicationError: getTodosByMonth" + t);
+                errorLiveData.setValue(parseStatusCode(-1));
+            }
+
+        });
+    }
+
+    public void getTodosByDay(String accountId,Integer bookId, Integer year, Integer month,
+                              Integer day, String token)
+    {
+        Call<HashMap<Integer, Todo>> call = todosRest.getTodosByDay(accountId, bookId, year, month, day, token);
+        call.enqueue(new Callback<HashMap<Integer, Todo>>() {
+            @Override
+            public void onResponse(Call<HashMap<Integer, Todo>> call, Response<HashMap<Integer, Todo>> response) {
+                if (response.isSuccessful()) {
+                    System.out.println("Success: getTodosByDay");
+                    TodosByDayLiveData.setValue(response.body());
+                } else {
+                    System.out.println("Error: getTodosByDay" + response.code());
+                }
+            }
+            @Override
+            public void onFailure(Call<HashMap<Integer, Todo>> call, Throwable t) {
+                System.out.println("CommunicationError: getTodosByDay" + t);
+                errorLiveData.setValue(parseStatusCode(-1));
+            }
+
+        });
+    }
+
+    public void getTodoById(String accountId,Integer bookId, Integer year, Integer month,
+                              Integer day, Integer todoId, String token)
+    {
+        Call<Todo> call = todosRest.getTodoById(accountId, bookId, year, month, day, todoId, token);
+        call.enqueue(new Callback<Todo>() {
+            @Override
+            public void onResponse(Call<Todo> call, Response<Todo> response) {
+                if (response.isSuccessful()) {
+                    System.out.println("Success: getTodoById");
+                    TodoByIdLiveData.setValue(response.body());
+                } else {
+                    System.out.println("Error: getTodoById" + response.code());
+                }
+            }
+            @Override
+            public void onFailure(Call<Todo> call, Throwable t) {
+                System.out.println("CommunicationError: getTodoById" + t);
+                errorLiveData.setValue(parseStatusCode(-1));
+            }
+
+        });
+    }
+
+    public void createTodo(String accountId,Integer bookId, Integer year, Integer month,
+                           Integer day, String title, String token)
+    {
+        Call<Todo> call = todosRest.createTodo(accountId, bookId, year, month, day, title, token);
+        call.enqueue(new Callback<Todo>() {
+            @Override
+            public void onResponse(Call<Todo> call, Response<Todo> response) {
+                if (response.isSuccessful()) {
+                    System.out.println("Success: createTodo");
+
+                } else {
+                    System.out.println("Error: createTodo" + response.code());
+                }
+            }
+            @Override
+            public void onFailure(Call<Todo> call, Throwable t) {
+                System.out.println("CommunicationError: createTodo" + t);
+                errorLiveData.setValue(parseStatusCode(-1));
+            }
+
+        });
+    }
+
+    public void setCheck(String accountId, Integer BookId, Integer year, Integer month,
+                           Integer day, Integer todoId, boolean check, String token)
+    {
+        Call<Void> call = todosRest.setCheck(accountId, BookId, year, month, day, todoId, check, token);
+        call.enqueue(new Callback<Void>() {
+            @Override
+            public void onResponse(Call<Void> call, Response<Void> response) {
+                if (response.isSuccessful()) {
+                    System.out.println("Success: setCheck");
+
+                } else {
+                    System.out.println("Error: setCheck" + response.code());
+                }
+            }
+            @Override
+            public void onFailure(Call<Void> call, Throwable t) {
+                System.out.println("CommunicationError: setCheck" + t);
+                errorLiveData.setValue(parseStatusCode(-1));
+            }
+        });
+    }
+
+    public void deleteTodo(String accountId, Integer BookId, Integer year, Integer month,
+                           Integer day, Integer todoId, String token)
+    {
+        Call<Void> call = todosRest.deleteTodoById(accountId, BookId, year, month, day, todoId, token);
+        call.enqueue(new Callback<Void>() {
+            @Override
+            public void onResponse(Call<Void> call, Response<Void> response) {
+                if (response.isSuccessful()) {
+                    System.out.println("Success: deleteTodo");
+
+                } else {
+                    System.out.println("Error: deleteTodo" + response.code());
+                }
+            }
+            @Override
+            public void onFailure(Call<Void> call, Throwable t) {
+                System.out.println("CommunicationError: deleteTodo" + t);
+                errorLiveData.setValue(parseStatusCode(-1));
+            }
+        });
+    }
+
+
+
+    private String parseStatusCode(Integer stats) {
+        switch (stats) {
+            case 404:
+                return "NotFound";
+            case 401:
+                return "InvalidToken";
+            case 400:
+                return "ResponseError";
+            case 500:
+                return "ServerError";
+            default:
+                return "UnknownError";
+        }
+    }
+}