Mahoutsukai Mana to H no Tobira

At the lowest level of a dungeon, a group of adventurers discovers what they believe to be the final treasure: a revealing swimsuit. After returning to town and parting ways, a wizard named Mana comes across the swimsuit while changing. Curious, she considers wearing it, unaware of the consequences. The item is described as unlocking a forbidden door leading to a realm of intense pleasure. The narrative presents this as a choice point, suggesting the possibility of crossing into an alternate experience.