[Y no Shokutaku (Hamada Yoshikadu)] Kazuma gets thoroughly cleaned out (Tsugumomo)

Kasumi barges into the bathroom where her brother Kazuma is soaking in the tub, stripping down without a shred of hesitation and announcing, "Sis and Kokuyou !!!! NAKED." Kazuma is cornered with nowhere to escape, his boner betraying him in front of both sisters as he tries desperately to cover up. Kazuma protests that they shouldn't be naked together—"Why are you both naked!? Shouldn't you both cover up with a towel or swimsuit at least..."—while Kasumi cheerfully suggests they could "try some cute stuff that you might guess." The situation escalates as Kokuyou grabs a soapy sponge and begins scrubbing Kazuma's chest, her ample breasts pressing close, with Kazuma admitting, "I'm in horny because of your nipples poking into my back." Things grow more intense as Kazuma offers to return the favor, pumping his sister with the pillow boob technique he recently discovered while Kokuyou gasps at the touch on her nipples. The teasing continues with Kazuma sharing fantasies about what he'd do to her that small butt she supposedly shouldn't be proud of, while her mind wanders to making him cum again, building toward a thoroughly serviced finale.