Onii-chan Is Done For!

Mahiro Oyama was an ordinary guy who loved playing adult games—until everything changed overnight. Waking up to find himself transformed into a woman, he quickly realized his genius but reckless little sister, Mihari, had used him as a test subject for one of her bizarre experiments. While Mahiro desperately wants to return to his reclusive gaming lifestyle, Mihari is obsessed with observing his new condition. Their opposing goals set the stage for a chaotic and unpredictable future, filled with absurd situations neither of them could have imagined. As Mahiro struggles to adapt, one thing becomes clear: his life will never be the same again. The experiment has thrown him into a world of confusion, embarrassment, and unexpected challenges. Mihari’s relentless curiosity only adds fuel to the fire, ensuring their days ahead will be anything but ordinary. With each passing moment, the line between science and absurdity blurs further, leaving Mahiro questioning what’s next. Whether he likes it or not, his quiet, uneventful days are over—replaced by a whirlwind of strange encounters and bizarre discoveries. The experiment may have altered his body, but it’s his entire existence that’s now turned upside down.