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.

Summer has come to Tempest. When he learns that summers here weren’t always this hot, Rimuru begins to fear that the change was his fault. Shuna and Shion have their own unique way to keep cool, and Rimuru tries to think up some fun summer activities… but bug-catching turns into bug-hunting when the bug he’s after turns out to be enormous, and a game of shooting water pistols gets out of hand when Rimuru himself becomes a water cannon. With everything on a completely different scale in Jura, every activity he tries turns into pure chaos! And Rimuru has no idea that he himself is the ideal cold pack…

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.

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.