Extreme summer heat is ravaging Tempest. Rimuru and crew visit a lake they’ve been told lies beyond the forest, and they change into swimsuits to start having fun… but Shion and Shuna seem dissatisfied with Rimuru’s swimsuit. Veldora watches the gang from inside Rimuru’s body as he plays a game of shogi with Ifrit. As the Storm Dragon, one who has never experienced swimsuits or water play, he struggles to understand what all the excitement is about…

If you use Shadow Movement to sneak into houses and a pegasus team to pull the flying sleigh... yes, in this world, it's possible to become Santa Claus! But... the Christmas tradition doesn't even exist in this world. When Rimuru tries to explain it in detail to the people of Tempest, they end up summarizing it as a "party." The Christmas cake and presents are ready, and most importantly, Kaijin and the other Dwarves create gorgeous decorations that bring the Christmas mood to Tempest. On top of that, Eren and the children treat everyone in town with their heavenly singing.