Level Drain.

Seasoned adventurer Orca Victoria, returning from a quest, was struck by a spell cast by a low‐level mushroom‐type monster. She later discovered it was a charm that imprinted a lewd mark upon her—and resolved to slay the mushroom monster to break the curse… However, under the influence of that mark, Orca found herself utterly powerless before the low‑level creature… (Source: DLsite, translated)