Syd Craft: Love is a Mystery

Asagami, a professional assassin is headed to complete her first mission, but discovers that her target, Hakuro Yosame, is immortal. In exchange for working for him as a maid, she can try to kill him as much as she wants.

The story tells us the day-to-day life of a cat trying to take care of his owner, a mangaka, so that she can meet her deadlines and responsibilities and not fall into the temptation of idleness for the sake of both of them. (Source: MangaDex)