Tanondara Yarerutte ero manga de yonda kara hahaoya ni onegaishitemita - I read in an erotic manga that if you ask...
Okaa-san no Waki no Nioi ga Tamaranai | I Can't Get Enough of Mom's Armpit Stench (COMIC Kuriberon DUMA Vol. 01)
[Pentacle (Shimipan)] Shikatanaku Kaa-chan to Sex Shimasu 4 - I Have No Choice But to Have Sex with My Mother 4 [English][DarklordMTLs]
A story about a mommy instructor of rural martial art who got brainwashed by a monster and transformed into a muscular combatant