Boku no Risou no Isekai Seikatsu

A forty-year-old unmarried man loses consciousness after pushing himself to the brink through excessive self-gratification, believing in his final moments that he has finally experienced life to its absolute limit. However, instead of fading into nothingness, he awakens to find a concerned young woman gazing down at him. She introduces herself as Misha and addresses him by the name Norun, explaining that he had nearly drowned in a nearby river. Bewildered by his surroundings, he looks into the water and discovers that his reflection is no longer that of an aging man, but rather a youthful, adorable boy adorned with animal ears. He has been reincarnated into a fantastical new world where every inhabitant possesses beast-like features such as ears and tails. This unfamiliar realm operates under unique societal norms, including a population heavily skewed toward women and a culture that embraces polygamy. Within this framework, Misha reveals that she is destined to become Norun's very first wife. Even though their marriage has not yet taken place, she already shares his home and exhibits a complete lack of hesitation regarding modesty, casually undressing to bathe alongside him. As Misha attentively washes his body, Norun finds his physical reactions growing increasingly difficult to control, signaling the provocative beginning of his unexpected second life.