Shiro Majo-san to no Henkyou Gurashi - Saikyou no Majo wa Nonbiri Kurashitai

Tori, who works as a handyman for the platinum-class clan "Four Horns of Mud", is fired from his job when the clans are merged. Just as he is at a loss as to what to do, the White Witch, a renowned and strongest adventurer, appears before him. The old woman, with the presence of an end-of-the-century champion, says she wants to hire Tori. Tori suspects that the White Witch is just making fun of him, and tries to implicitly refuse by offering a high salary, but she readily accepts and takes him to the witch's house.As Tori kneels down and apologizes, the White Witch, who was supposed to be an old woman, transforms into a cute young girl and says, "Your first job... I'd like you to clean."

https://www.cmoa.jp/title/303657/