diff --git a/test.py b/test.py
index b2bde57..29747dc 100644
--- a/test.py
+++ b/test.py
@@ -108,16 +108,19 @@ class Game:
     ゲーム・クラス
 
     Attributes:
-        clock (Clock):              Clock オブゼクト
-        frame (int):                フレーム・カウンタ
-        redrawers (list[Redrawer]): 再描画するクラスのリスト
-        screen (Surface):           基底スクリーン
-        sky (Sky):                  天体情報
+        clock (Clock):                  Clock オブゼクト
+        frame (int):                    フレーム・カウンタ
+        last_answered_at (datetime):    最後に回答した時刻
+        now (datetime):                 基準日時
+        redrawers (list[Redrawer]):     再描画するクラスのリスト
+        screen (Surface):               基底スクリーン
+        sky (Sky):                      天体情報
     """
 
     clock:              Clock
     frame:              int
     last_answered_at:   datetime
+    now:                datetime
     redrawers:          list[Redrawer]
     screen:             Surface
     sky:                Sky
@@ -134,6 +137,8 @@ class Game:
     def redraw (
             self,
     ) -> None:
+        self.now = datetime.now ()
+        self.sky.observer.date = self.now - timedelta (hours = 9)
         for redrawer in sorted (self.redrawers, key = lambda x: x['layer']):
             if redrawer['obj'].enabled:
                 redrawer['obj'].redraw ()
@@ -339,7 +344,7 @@ class CurrentTime (GameObject):
     ) -> None:
         for i in range (4):
             self.game.screen.blit (
-                    self.font.render (str (datetime.now ()), True, (0, 0, 0)),
+                    self.font.render (str (self.game.now), True, (0, 0, 0)),
                     (i % 2, i // 2 * 2))
         super ().redraw ()
 
@@ -384,7 +389,7 @@ class Balloon (GameObject):
     ) -> None:
         if self.frame >= self.length:
             self.enabled = False
-            self.game.last_answered_at = datetime.now ()
+            self.game.last_answered_at = self.game.now
             return
         query = self.query
         if CommonModule.len_by_full (query) > 21:
@@ -451,7 +456,6 @@ class KitaSun (GameObject):
         surface = pygame.transform.rotate (self.surface, -(90 + math.degrees (self.arg)))
         self.game.screen.blit (surface, surface.get_rect (center = (self.x, self.y)))
         super ().redraw ()
-        self.game.sky.observer.date = datetime.now () - timedelta (hours = 9)
         self.sun.compute (self.game.sky.observer)
         self.alt = self.sun.alt
         self.az = self.sun.az
@@ -488,11 +492,14 @@ class Jojoko (GameObject):
     Attributes:
         base (Surface):     満月ヨヨコ Surface
         moon (Moon):        ephem の月オブゼクト
-        surface (Surface):  缺けたヨヨコ Surface
+        surface (Surface):  缺けたヨヨコ
     """
 
+    alt:        float
+    az:         float
     base:       Surface
     moon:       Moon
+    surface:    Surface
 
     def __init__ (
             self,
@@ -500,25 +507,43 @@ class Jojoko (GameObject):
     ):
         super ().__init__ (game)
         self.base = pygame.transform.scale (pygame.image.load ('assets/moon.png'), (200, 200))
+        self.moon = Moon ()
+        self.surface = self._get_surface ()
 
     def redraw (
             self,
     ) -> None:
-        ...
+        if self.frame % 300 == 0:
+            self.surface = self._get_surface ()
+        surface = pygame.transform.rotate (self.surface, -(90 + math.degrees (self.arg)))
+        surface.set_colorkey ((0, 255, 0))
+        self.game.screen.blit (surface, surface.get_rect (center = (self.x, self.y)))
+        super ().redraw ()
+        self.moon.compute (self.game.sky.observer)
+        self.alt = self.moon.alt
+        self.az = self.moon.az
+        if abs (self.new_arg - self.arg) > math.radians (15):
+            self.arg = self.new_arg
+        self.x = self.new_x
+        self.y = self.new_y
 
     @property
     def phase (
             self,
     ) -> float:
         dt: datetime = ephem.localtime (ephem.previous_new_moon (self.game.sky.observer.date))
-        return (datetime.now () - dt).total_seconds () / 60 / 60 / 24
+        return (self.game.now - dt).total_seconds () / 60 / 60 / 24
 
-    @property
-    def surface (
+    def _get_surface (
             self,
     ) -> Surface:
+        """
+        ヨヨコを月齢に応じて缺かす．
+
+        Returns:
+            Surface:    缺けたヨヨコ
+        """
         jojoko = self.base.copy ()
-        jojoko.set_colorkey ((0, 255, 0))
         for i in range (200):
             if 1 <= self.phase < 15:
                 pygame.gfxdraw.bezier (jojoko, ((0, 100 + i), (100, 180 * self.phase / 7 - 80 + i), (200, 100 + i)), 3, (0, 255, 0))
@@ -530,6 +555,26 @@ class Jojoko (GameObject):
                 jojoko.fill ((0, 255, 0))
         return jojoko
 
+    @property
+    def new_x (
+            self,
+    ) -> float:
+        return CWindow.WIDTH * (math.degrees (self.az) - 80) / 120
+
+    @property
+    def new_y (
+            self,
+    ) -> float:
+        return ((CWindow.HEIGHT / 2)
+                - ((CWindow.HEIGHT / 2 + 100) * math.sin (self.alt)
+                   / math.sin (math.radians (60))))
+
+    @property
+    def new_arg (
+            self,
+    ) -> float:
+        return math.atan2 (self.new_y - self.y, self.new_x - self.x)
+
 
 class Sky:
     """