diff --git a/kadai4/yasu/controllers/rottely_controller.go b/kadai4/yasu/controllers/rottely_controller.go
new file mode 100644
index 0000000..6076717
--- /dev/null
+++ b/kadai4/yasu/controllers/rottely_controller.go
@@ -0,0 +1,23 @@
+package controllers
+
+import (
+	"dojo4/kadai4/yasu/controllers/serializer"
+	"dojo4/kadai4/yasu/services"
+	"encoding/json"
+	"net/http"
+)
+
+func DevineFortune(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	fortune, err := services.Rottely()
+	if err != nil {
+		response := serializer.Error{Err: err}
+		w.WriteHeader(http.StatusInternalServerError)
+		json.NewEncoder(w).Encode(response)
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+	response := serializer.RottelyResult{Fortune: fortune}
+	json.NewEncoder(w).Encode(response)
+}
diff --git a/kadai4/yasu/controllers/rottely_controller_test.go b/kadai4/yasu/controllers/rottely_controller_test.go
new file mode 100644
index 0000000..dd8af39
--- /dev/null
+++ b/kadai4/yasu/controllers/rottely_controller_test.go
@@ -0,0 +1,29 @@
+package controllers
+
+import (
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func DevineFortuneTest(t *testing.T) {
+	w := httptest.NewRecorder()
+	r := httptest.NewRequest("GET", "/rottely", nil)
+	DevineFortune(w, r)
+	res := w.Result()
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusOK {
+		t.Fatal("unexpected status code")
+	}
+
+	bytes, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		t.Error(err)
+		t.Fatal("unexpected error")
+	}
+	if fortune := string(bytes); fortune == "" {
+		t.Fatalf("unexpected response: %s", fortune)
+	}
+}
diff --git a/kadai4/yasu/controllers/serializer/error.go b/kadai4/yasu/controllers/serializer/error.go
new file mode 100644
index 0000000..091b73e
--- /dev/null
+++ b/kadai4/yasu/controllers/serializer/error.go
@@ -0,0 +1,5 @@
+package serializer
+
+type Error struct {
+	Err error
+}
diff --git a/kadai4/yasu/controllers/serializer/rottely_serializer.go b/kadai4/yasu/controllers/serializer/rottely_serializer.go
new file mode 100644
index 0000000..5d91330
--- /dev/null
+++ b/kadai4/yasu/controllers/serializer/rottely_serializer.go
@@ -0,0 +1,5 @@
+package serializer
+
+type RottelyResult struct {
+	Fortune string `json:"fortune"`
+}
diff --git a/kadai4/yasu/main.go b/kadai4/yasu/main.go
new file mode 100644
index 0000000..4084cdf
--- /dev/null
+++ b/kadai4/yasu/main.go
@@ -0,0 +1,13 @@
+package main
+
+import (
+	"dojo4/kadai4/yasu/controllers"
+	"net/http"
+)
+
+func main() {
+
+	http.HandleFunc("/rottely", controllers.DevineFortune)
+
+	http.ListenAndServe(":8080", nil)
+}
diff --git a/kadai4/yasu/services/rottely_service.go b/kadai4/yasu/services/rottely_service.go
new file mode 100644
index 0000000..907cdb1
--- /dev/null
+++ b/kadai4/yasu/services/rottely_service.go
@@ -0,0 +1,62 @@
+package services
+
+import (
+	"errors"
+	"math/rand"
+	"time"
+)
+
+func Rottely() (string, error) {
+	var randomInt int
+	var fortune string
+	var err error
+	location, _ := time.LoadLocation("Asia/Tokyo")
+	now := time.Now().In(location)
+	newYearsDay := time.Date(2018, 1, 1, 0, 0, 0, 0, location)
+	endDay := time.Date(2018, 1, 4, 0, 0, 0, 0, location)
+	if !now.Before(newYearsDay) && !now.After(endDay) {
+		fortune = "大吉"
+	} else {
+		rand.Seed(time.Now().UnixNano())
+		randomInt = rand.Intn(17)
+		switch randomInt {
+		case 0:
+			fortune = "大大吉"
+		case 1:
+			fortune = "大吉"
+		case 2:
+			fortune = "向大吉"
+		case 3:
+			fortune = "末大吉"
+		case 4:
+			fortune = "吉凶末分末大吉"
+		case 5:
+			fortune = "吉"
+		case 6:
+			fortune = "中吉"
+		case 7:
+			fortune = "小吉"
+		case 8:
+			fortune = "後吉"
+		case 9:
+			fortune = "末吉"
+		case 10:
+			fortune = "吉凶不分末吉"
+		case 11:
+			fortune = "末凶相交末吉"
+		case 12:
+			fortune = "吉凶相半"
+		case 13:
+			fortune = "吉凶相央"
+		case 14:
+			fortune = "小吉後吉"
+		case 15:
+			fortune = "凶後吉"
+		case 16:
+			fortune = "凶後大吉"
+		default:
+			err = errors.New("Rottely error: Invalid integer")
+		}
+	}
+	return fortune, err
+}