Mamono no Ongaeshi is a completed manga by Torihara Shuu, first published in 2020. It blends romance, comedy, fantasy and slice of life. You can read all 3 available chapters of Mamono no Ongaeshi online for free on MangaPulse; the newest is Chapter 3, added 2020-12-05. The series is finished, so you can read it from start to end in one go.