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.

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...

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.

Rimuru said he wanted to do a first shrine visit of the new year, so the citizens of Tempest built a shrine. But what deity is housed at this brand new shrine? Rimuru thought it must be Veldora, the guardian of the Forest of Jura, but everyone else says it's a shrine to Great Rimuru, so he ends up enshrined there... Thus their fun New Year's comes to an end, and Rimuru closes his diary. What will this new year bring? Tomorrow is sure to be packed with enough events to fill a new page...