Takuya Aihara

Takuya Aihara is the perennially unlucky protagonist of the main X-Change games. As a part of the Chemistry Club in Miyanomori Private School (NOTE: the characters are all in junior college in US localizations of the game due to child pornography laws) he was twice transformed into a girl and twice recovered according to the canonical ending. The third game had Takuya majoring in Chemistry at the university level when he is transformed yet again and recovers yet again, but not without sexual exploits in all three cases.

Takuya's girlfriend in all the "main" endings is Asuka Katakiri, but each game features alternate endings where Takuya can end up with other women or even remain a girl and end up with a man.

X-Change

Takuya's first encounter with sex-changing science comes his junior year at Miyanomori Private School. While cleaning up the Chemistry Club room after school one day, he accidentally spills a chemical on a finger which he had just cut to do an experiment with luminol. Much to his surprise, he later wakes up in a female body. A little help from his step-sister Natsumi and his childhood friend Asuka gets him a girl's school uniform and other girl's clothing as he begins to experience life on the other side. He soon learns from Chemistry Club president Asami Satoh that there is a deadline for him to transform back or risk remaining a woman forever. There are multiple, sex-filled paths for Takuya to take resulting in him becoming a man again or staying a woman and he can either end up alone or with Asuka or Satoh. Series canon has Takuya regain his masculinity and confess his love to Asuka. The two fall in love and begin dating.

X-Change 2

Takuya is still with Asuka and is now a senior at Miyanomori Private School. He is also president of the Chemistry Club whose other members now include Koji Kudo and Satoh's rival, Chisato Kawahara. Lured in with promises of becoming taller and, hence, more masculine, Takuya participates in an experiment conducted by Chisato and ends up a woman yet again. Takuya is once again faced with a strict deadline to become a man once again, only this time progress is threatened by lack of funds and Koji. To correct these problems Takuya must take on a part-time job and avoid Koji who fell in love with Takuya in X-Change after he took his virginity. Like before, there are multiple paths and multiple endings, but the canonical ending has Takuya regain his proper gender and end up yet again with Asuka.

X-Change 3

Now a Chemistry major in college, Takuya finds himself transformed yet again, this time as a result of Koji's schemes. After getting Takuya to drink a spiked drink filled with Satoh's sex-changing potion, it becomes a race against time to return to male form yet again. Despite putting up with straight occurances, Asuka's patience is wearing thin and she's tired of Takuya's weak ways. Takuya manages to cure himself yet again and rededicate himself to his major, winning Asuka back in the process in the canonical ending.