[Tiba-Santi (Misuke)] Dungeon Travelers - Manaka no Himegoto 1.5 (ToHeart2)

Kind-hearted priestess Manaka ventures into a monster-infested dungeon and takes pity on a colony of giant insects, offering herself so the poor creatures can finally breed. The swarm wastes no time swarming her big breasts, thick thighs, and every exposed inch of her, their copulation organs probing eagerly as narration wryly notes she has become both treat and food for the ravenous bugs. What started as compassion turns into an overwhelming, full-body ordeal as Manaka learns exactly how one big mistake in the dungeon depths gets repaid.