SISTER RESISTER

 I stumbled across this very short-lived (6 installments) harem comedy, YOKAI LOVE ATTACK. Despite the dull protagonist having his virginity endangered by a half-dozen demonesses, the guy's main threat seems to be his blood sister Tsunako Minamoto. Mostly she just bullies him, though one episode suggests some bro-curiosity. The denouement is rushed, suggesting the feature got so little response that the artist was told to wrap things up.

       

ADDENDA-- Two of more formidable demons both have "older woman" vibes, the first an unnamed seduction-demon who tells students to call her mommy and suck her tits, the second a homeroom teacher named Unahara, who's also a "sea woman."