[Ogino Satoshi] Seikatsubu e Youkoso Zenpen (JK Genkai Koubi ~Goui Sounyuu de Bachibachi Nikuana-ka~) [CGrascal]

When the school moves to reclaim the Seikatsu Club's room, Rina refuses to let her club die without proving its worth, dragging her flustered classmate Shouta in as both research subject and partner. Armed with a clipboard and zero shame, she sizes up his surprisingly impressive cock, smothers it between her huge breasts for a hands-on lesson in stimulation, then rides him through a full activity report that ends with his first load pumped deep inside her pussy. Grade stamped and teacher none the wiser, Rina is already eager to keep improving their sexual life — and with a 'to be continued' looming, this is only the first part.