Reiichi accidentally develops an intelligent AI who takes the form of a cute (and very young-looking) girl called Apeiria who makes her own massive network and has her create a complex VRMMO that mirrors all of the real world’s sensations and basic physics but with a magic system. After a day, the VRMMO turns into a ‘if you get forcibly logged out (through in-game death), you die irl” death game and Apeiria gets held captive by the game’s very system. The rest of the game is then a time-leaping adventure to save the loli AI, with loads of quantum mechanics infodumping and diagrams. And also lots of dick jokes. Reiichi’s power in the VRMMO is a literal dick sword that requires ejaculation in exchange for gamebreakingly powerful attacks.