[Yuna] Hypnosis Pencil ~Oji-san Katei Kyoushi to Kyouei Mizugi JK no Man-to-man Saimin Gakushuu~ Zenpen (COMIC Grape Vol. 98) [SquigglesJP]

Saki, a swim club girl fresh off retirement and staring down exam season, takes on a private tutor whose one-on-one lessons turn hands-on fast. Guided by his strange hypnosis pencil, the big-breasted schoolgirl gets a 'study session' of cunnilingus that leaves her gasping, a bouncing cowgirl ride with her plush ass on full display, and a deep, sweaty drilling that wrings a shuddering orgasm out of her—all while she half-believes it's just exam prep. Showering afterward with a lightheaded fuzz she can't explain and a nagging suspicion about that pen, she senses this session is only the beginning, to be continued.