Arifureta: From Commonplace to World's Strongest (Manga) Vol. 7

Hajime's life is one over-the-top adventure after another, but against all odds, Shea manages to convince him to take a break from all the madness and go out on a date. Unfortunately, trouble has a way of finding Hajime regardless. The two of them wind up face-to-face with Myu, a young mermaid who's fallen into the clutches of a nefarious organization. Does Hajime maybe have a huge paternal soft spot for this little aquatic girl...?