The Misfit of Demon King Academy (WN) - Chapter 19.1

What the heck? She, a famous doctor from the 23rd century, turned into a village peasant girl of a different world!

A slime randomly falls into existence. Sapient and born with the ability to recreate parts of the things it preys upon, the highly confused drop of primordial soup decides that the only real thing it can do is become the being at the top of the food chain. A task of longevity in the leaves of the Omniverse.

This is probably the story of a modern man who became the Seventh son of Kangxi in the Qing Dynasty. This is probably the story of how the Seventh brother Yinyou worked hard and fell in love by the way. So there is no doubt that this article is ambiguous, and it is easy to guess who the couple is.

- Description from Novelupdates