I Start by Tricking Muzan and Voldemort

Gender transformation, yuri, and children.

This book has no System.

There’s character development and farming.

Zhang San, the third child in his family, transmigrates into Demon Slayer. A grown man wakes up in a woman’s body, and not just any woman’s: he’s a sixteen-year-old girl who has just been turned into a demon by Muzan! How is he supposed to live like this...

He talks Muzan into changing her ways, and the change in the rotten Muzan is huge. He even manages to lead Muzan into thoroughly misleading the Demon Slayer Corps.

He drags Muzan out of Japan, where she’s been living a life of comfort, so she’ll stop sitting at home all the time.

Later, he fools Voldemort’s parents, raises Voldemort to go astray from an early age, and learns magic along the way. He causes all kinds of trouble at Hogwarts School of Witchcraft and Wizardry, then keeps tormenting Harry Potter years after graduation.

He even gets involved in World War II, fools Tanya von Degurechaff, and so on and so forth.

Ahem, people should enjoy life. Now that he has an infinite lifespan, of course he’s going to spend it eating, drinking, and having fun.

His motto: You only live once, so make sure you enjoy it.

All the hard work early on is so he can lie flat later.