The hentai series 'Boin' plunges viewers into the debaucherous activities of the high school Boin Club, a group dedicated to the 'scientific' exploration of massive tits. The story follows Daisaku, a new member who is quickly initiated into their hardcore research. Led by the insatiable and gigantically-endowed student council president Nao, the club's activities escalate from simple breast worship and tit-fucking into full-blown group orgies. Each episode showcases different club members and guest girls getting their huge breasts groped, sucked, and fucked. The arc sees the girls pushing their sexual limits, engaging in intense lesbian scissoring, getting covered head-to-toe in cum, and using their massive mammaries to pleasure each other and any lucky bastard who stumbles upon them. The entire series is a cum-drenched celebration of busty sluts getting used in every conceivable way, culminating in massive, dripping orgies where every pair of tits gets a thick, creamy facial.