Doukyuusei Kaizou ~Namaiki Musume wa Jikkendai ni Shiteshimae!~

The protagonist, Kagano Takeshi, is a student who studies diligently every day, aiming to get a doctorate in biology. Looking down on his classmates for their superficial conversations, he spent his time in silence at home, immersed in his own experiments. One day, Kagano developed a "cell rejuvenation drug". When he tested it on mice, the cells did not actually rejuvenate; instead, their chests swelled and the females developed organ-like growths resembling reproductive systems. Furthermore, they appeared to be in an abnormal state of heat. Although there were no lethal side effects, Kagano was disappointed. His frustration then turned toward Miki, who always teased him. "I'll make her drink this drug". And so began Kagano's experiments to modify Miki... [MTL translation from the official site]