Sensei, Ore ni Kamawazu Itte Kudasai!! - Vol. 6 Ch. 44 - 44th Manuscript

[MangaDex]

 

[MasterCastro]

Bruh, not the little brother...
For it to be aching... That's at least 16 times.

 

[SpecialProjectY]

Well, oblivious as usual, she's an exhibitionist and likes to be seen when masturbating, it's what makes her more turn on.

Mamoru begins to mindbreak, wanking off won't solve the problem but... age gap still is a problem for now...