Yoku Wakaranai keredo Isekai ni Tensei Shiteita You desu

Reincarnated into a fantasy realm in the body of an adorable orphan girl, Ren appears destined for a life of hardship after being sold off. However, everything changes when a sudden carriage accident triggers memories of her past existence. To her utter shock, the sweet young girl discovers she was once a thirty-something male researcher in her previous life. Now possessing the unique combination of a youthful form, adult intellect, and profound scientific knowledge, Ren must navigate a harsh world defined by magic and danger. Utilizing her past expertise alongside newly awakened magical talents, she plots a resourceful strategy to survive and break free from the ruthless investor who originally purchased her.