Heart Mark Oome OVA

Segawara Yu lives with his older stepsister Reika, a reclusive erotic manga artist whom he cooks and cares for daily. Ever since she became a full-time artist, Reika has had a habit of forcing herself on Yu whenever she finishes a manuscript, having pent up her desires while drawing — a routine that has since become a regular part of their lives. Yu is conflicted, acknowledging the taboo nature of their relationship while being unable to resist Reika’s advances, and privately worries that she sees him as nothing more than a convenient outlet. The episode culminates in a marathon session where Reika dresses as a succubus — the theme of her latest work — and pushes Yu to his absolute physical limit before he passes out