Natsuzuma

Overview

A summer trip to the beach that she couldn't go to with her husband. Yumiko was excited and looking forward to this day. But when her husband can't come, she heads to the beach alone with her young son. Just as she's feeling down, two young men approach her. That night, Yumiko is invited to the room of the men who hit on her that day. She puts her son to bed and heads to the room where the two young men are waiting, with secret hope in her heart. A forbidden summer begins, as she is consumed by carnal desires despite being tormented by guilt... (Source: Lune-soft, translated)

Source: AniList