As he’s living out his amazing slime life, Rimuru decides to record his experiences in a diary… but there are so many, he doesn’t know where to start. That’s just how life in Tempest goes.

Peace has come at last following the battle against the Orc Lord. In the midst of the duties that keep him busy, Rimuru finds himself with a day off. But when he tries to enjoy the break, he can’t even figure out what to do and just ends up bored. He heads into town with Gobta to eat some food from the street stalls as they walk around, but in the end, he only feels more motivated to work the fields.

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…

Rimuru decides to throw a summer festival resembling the ones held in Japan. The monsters have never experienced a summer festival, but when they hear that it's a party, they go all-in to prepare. All the monsters of Tempest work together and eventually come up with masks, paper lanterns, and even festival floats. On the day of the festival, everyone in the town enjoys piping hot takoyaki, cold shaved ice, yukata, and a Bon dance. In the end, they fill the skies with fireworks as the festival reaches its climax...

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...

In Great Sage's recollection, all seems to be smooth sailing for Tempest... but then the oldest of the Demon Lords, Milim Nava, arrives! Rimuru, as Milim's bestie, is appointed by the majority to be in charge of keeping an eye on her. With no knowledge of this, Milim explores Tempest and interacts more with the residents of the city of monsters... and Rigurd keeps track of all the damage she causes along the way in a report for Rimuru. "Rigurd... are you angry?"

It's autumn, and time for the harvest. Under the orders of Ririna, the Goblina in charge of the harvest, Gobta and his buddies get to work in the fields. Meanwhile, Shion and Milim make a contest out of digging up the sweet potatoes. With everyone working together, the harvest is over in practically no time, and Rimuru and the rest of the gang finally get to enjoy some delicious roasted sweet potatoes.

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.