WARNING: The following contains spoilers for Episode 2 of The Slime Diaries "The Air in Spring and..." now streaming on Crunchyroll.
Rimuru is the iconic, namesake slime from That Time I Got Reincarnated As A Slime, and in the new spin-off The Slime Diaries, his work ethic is put to the test. Ever since being isekai'd into a fantasy world and becoming a slime, Rimuru has been kept busy from one moment to the next. From running into and helping hordes of monsters to founding his own city, Rimuru is an exceptionally busy guy. So when Episode 2 of The Slime Diaries confronts him with an unexpected day off, he doesn't know what to do.
Things have begun to settle down in Tempest and Rimuru's schedule is surprisingly clear for the first time ever, and at first, he looks forward to it. But after a while of doing nothing, Rimuru starts to fidget and become restless. It becomes so bad that he looks to Shion and Geld for any work not long after being told he has a day off.
Rimuru hangs around with Gobta, who is actually just playing hooky and experiences a little bit of his own town in a new way, exploring the shops and snack stands. After a while just wandering around, Rimuru makes his way back to his offices, where he starts to hide from Shion and play around, splitting himself into many pieces just for the fun of it. Luckily for him, soon after it's announced that it's about time to start plowing and seeding the new farming fields. Rimuru is ecstatic because now there's work to be done.
While out in the fields, Rimuru supervises in slime form and contributes to the labor in human form. As long as there's work to be done, Rimuru will be there. Even supposed grunt work, like plowing and planting on a sunny day, is better than being restless with nothing to do. Especially since this work will yield edible results.
Rimuru's addiction to work makes total sense. He formed a habit early on in the original anime to always be helping someone or attending to someone else's needs. Once a habit is formed, not only is it hard to be aware of, but it's difficult to stop. So of course when Rimuru is told that there's no work to be done, he's uncomfortable. After months and months of always having something to do or someone to help, having nothing to do is unfamiliar territory to Rimuru. He literally doesn't know what to do with himself.
But it's not necessarily a bad thing that Rimuru is a workaholic. The Slime Diaries spends time with the characters during their day-to-day lives, excluding the plot-driven events and chaos of the original anime. Rimuru always having something to do simply means that he's improving Tempest in some way and making the lives of its citizens even better, day by day. While it's funny and a little sad to watch Rimuru struggle with downtime, it just means that he'd rather be doing something to contribute to the city and the people that he brought together. It's not such a bad thing to be a workaholic after all.