Inside a mysterious cauldron, magical cards swirl together and decide what players must follow. Rather than relying only on the cards in hand, players must watch the shared cauldron carefully, using its contents as a shifting source of suit obligation. Winning requires restraint, timing, and a little magical intuition, since taking too many tricks can be just as dangerous as taking too few.

Must Follow wa Kama no Naka (« Must-Follow Is in the Cauldron ») is a trick-taking game in which the follow-suit obligation is determined not only by the cards in players’ hands, but by cards placed in a shared “cauldron” area. Players may play cards from their hand or from the cauldron, and when a card is played from the cauldron, the player replenishes it with a card from their hand. The led suit determines the suit to follow, but players check the cauldron, not their hand, to see whether they are able to follow. The highest card of the led suit wins the trick, while rank 12 cards count as additional tricks. Players score based on taking a specific number of tricks according to player count, and the game rewards careful control, since the goal is not to win as many tricks as possible.