diff --git a/kadai4/main.go b/kadai4/main.go
new file mode 100644
index 0000000..8158735
--- /dev/null
+++ b/kadai4/main.go
@@ -0,0 +1,30 @@
+package main
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/gopherdojo/dojo6/kadai4/omikuji"
+)
+
+func main() {
+	http.HandleFunc("/", handler)
+	http.ListenAndServe(":8080", nil)
+}
+
+type Response struct {
+	Msg string `json:"msg"`
+}
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+
+	omikuji := omikuji.Omikuji{time.Now()}
+	res := Response{omikuji.Do()}
+
+	if err := json.NewEncoder(w).Encode(res); err != nil {
+		log.Println("Error:", err)
+	}
+}
diff --git a/kadai4/main_test.go b/kadai4/main_test.go
new file mode 100644
index 0000000..6d03145
--- /dev/null
+++ b/kadai4/main_test.go
@@ -0,0 +1,37 @@
+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestHandler(t *testing.T) {
+	w := httptest.NewRecorder()
+	r := httptest.NewRequest("GET", "/", nil)
+	handler(w, r)
+	rw := w.Result()
+
+	defer rw.Body.Close()
+
+	if rw.StatusCode != http.StatusOK {
+		t.Fatalf("unexpected status code: %d", rw.StatusCode)
+	}
+
+	b, err := ioutil.ReadAll(rw.Body)
+	if err != nil {
+		t.Fatal("unexpected error")
+	}
+
+	res := &Response{}
+	const expected = "大吉"
+	if err := json.Unmarshal(b, res); err != nil {
+		t.Fatalf("JSON unmarshall error: %v", err)
+	}
+
+	if res.Msg != string(expected) {
+		t.Fatalf("unexpected response: %s", res.Msg)
+	}
+}
diff --git a/kadai4/omikuji/omikuji.go b/kadai4/omikuji/omikuji.go
new file mode 100644
index 0000000..902892c
--- /dev/null
+++ b/kadai4/omikuji/omikuji.go
@@ -0,0 +1,36 @@
+package omikuji
+
+import (
+	"math/rand"
+	"time"
+)
+
+var omikuji = []string{
+	"凶",
+	"末吉",
+	"小吉",
+	"中吉",
+	"吉",
+	"大吉",
+}
+
+type Omikuji struct {
+	Time time.Time
+}
+
+func (o *Omikuji) SetSeed(seed int64) {
+	rand.Seed(seed)
+}
+
+func (o *Omikuji) Do() string {
+	var i int
+
+	_, m, d := o.Time.Date()
+	// 1/1 ~ 1/3のみ大吉を出す
+	if int(m) == 1 && d >= 1 && d <= 3 {
+		return "大吉"
+	}
+
+	i = rand.Intn(len(omikuji))
+	return omikuji[i]
+}
diff --git a/kadai4/omikuji/omikuji_test.go b/kadai4/omikuji/omikuji_test.go
new file mode 100644
index 0000000..b16262c
--- /dev/null
+++ b/kadai4/omikuji/omikuji_test.go
@@ -0,0 +1,37 @@
+package omikuji_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/gopherdojo/dojo6/kadai4/omikuji"
+)
+
+func Test_NormalTime(t *testing.T) {
+	time := time.Date(2019, time.Month(8), 16, 0, 0, 0, 0, time.Local)
+	omikuji := omikuji.Omikuji{time}
+	expect := "大吉"
+	actual := omikuji.Do()
+	if expect != actual {
+		t.Errorf(`Omikuji error: expect="%s" actual="%s"`, expect, actual)
+	}
+}
+
+func Test_SpecificPeriod(t *testing.T) {
+	periods := map[int][]int{
+		1: {1, 2, 3},
+	}
+
+	expect := "大吉"
+
+	for m, days := range periods {
+		for _, d := range days {
+			time := time.Date(2019, time.Month(m), d, 0, 0, 0, 0, time.Local)
+			omikuji := omikuji.Omikuji{time}
+			actual := omikuji.Do()
+			if expect != actual {
+				t.Errorf(`Omikuji error: expect="%s" actual="%s"`, expect, actual)
+			}
+		}
+	}
+}