As the seasons turn, Rimuru plans a Bon Festival celebration. Each race has its own history, and the festival is a time to show gratitude and reaffirm their bonds among their own families and clans, and to strengthen friendships by telling others all about their own histories. And with this Bon Festival, Shizu-san returns to Tempest as a spirit...

Most buildings in the monster city of Jura are made of wood, so in winter, a combination of dryness and heating mechanisms can lead to fires. So Rimuru starts up a good old-fashioned fire awareness campaign. Benimaru is selected as the mascot, but he seems troubled by the assignment... And in the midst of all these, the human Youm and his friends arrive in Tempest.

Winter has arrived in Tempest, and so much snow has fallen that its residents can't open their doors until it's shoveled away. But there are at least three like minds there who are finding it hard to resist their childlike urges to dive into the fresh snow: Rimuru, Milim, and Shion. Thus the work begins all around town to shovel Tempest out of the deep snow. Youm objects to being asked to help since he isn't even a citizen, but when he's given the choice between shoveling snow and training with Hakuro, he eagerly grabs the shovel and gets to work.

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.