Liu Wei, Cai Haoyu, and Lu Yuhao. Now billionaires.
Mihoyo was founded by three college students: Liu Wei (aka Da Wei), Cai Haoyu, and Luo Yuhao. They named their first game engine Misato, after the character from Evangelion. They formed a company and decided to name it Hoyo, taken from the first letters of Haoyu and Yuhao's names. The O was added because many famous tech companies like Google, Facebook, and Yahoo had Os in their name. When they went to register their company, they found out Hoyo had already been taken, so they added Mi to it and named it Mihoyo.
Misato from Evangelion
Their first game was FlyMe2theMoon, named after the Evangelion ending song. Unfortunately, it was a buy to play game in China where piracy was rampant (for various reasons, namely that the CCP would alternate between banning and legalizing foreign consoles, and restricted the number of foreign games that could be published in China each year. So Chinese gamers had become accustomed to simply sidestepping this nonsense and just pirating), so it did not help Mihoyo very much. So their next game, Houkai Gakuen (themed after Highschool of the Dead) was made into a live service game so that it could not be pirated (pretty much what almost all of the other Chinese game devs were doing). Houkai in Japanese means "collapse" or "decay", and Gakuen means "academy" (because the devs were still students). The titular Houkai are the enemy mobs you fight and supernatural in nature, causing apocalypses. The game did well.
Mihoyo reinvested their money and made a better sequel, Houkai Gakuen 2, which did better. Then they reinvested their money again and made an even better game named Honkai Impact 3rd. Mihoyo dropped the Gakuen because they weren't students anymore. HI3 was Mihoyo's darling game, where they created characters that they fell in love with and have been creating rehashes/expies of those characters for their next games Genshin and HSR. Raiden Shogun and Yae Miko from Genshin, Acheron and Phainon from HSR, etc, are rehashes/expies/alternate universe versions of HI3 characters. Houkai was changed to Honkai. The Impact part is another Evangelion reference (that show takes place in the aftermath of a calamity called Second Impact, which was caused by supernatural beings and wiped out most of the Earth, and the imminent threat of a Third Impact).
Mihoyo's next game was Genshin Impact. Genshin means "original god". The immdiete plot of each arc has you interact with the "god" of that arc's region, called an Archon, and there is a greater overarching plot about overthrowing gods in the floating island of Celestia who are responsible for the state of the Genshin world. And Mihoyo carried over the "Impact" name from HI3 to retain continuity.