FIXED: 9th Dan is the highest possible Dan, so you can't advanced higher with 3 wins in an row.

src/mahjong_ranking/models.py

@@ -313,7 +313,7 @@ class Hanchan(models.Model):
                       reverse=True)
 
     def save(self, **kwargs):
-        self.season = self.event.mahjong_season or date.today().year
+        self.season = self.event.mahjong_season or self.start.year
         self.full_clean()
         self.compute_player_placements()
         return models.Model.save(self, **kwargs)
@@ -361,7 +361,7 @@ class KyuDanRanking(models.Model):
         else:
             self.wins_in_a_row = 0
 
-        if self.dan and self.wins_in_a_row >= 3:
+        if self.dan and self.wins_in_a_row >= 3 and self.dan < 9:
             logger.info('adding bonuspoints for 3 wins in a row for %s', self.user)
             new_dan_rank = self.dan + 1
             new_dan_points = DAN_RANKS_DICT[new_dan_rank] + 1