Ciel is done with Rimuru constantly pushing work on her and decides to punish him by sending him into another world and cutting off his communication with his friends and subordinates. Of course, the unfortunate world that he is sent to is the one well a human is supposed to fall down. Well, guess they have to make do with a slime. (Again, like my Peck in Time fanfic, I couldn't find a "What if Rimuru was in Undertale" fanfic so here we are. This might be a bit badly written as I literally wrote it at random times.)
3 parts