CORRECTOR YUI

In the year 2000-something, a massive central network called Comnet links the computers of the world, forming a single global computer system. Comnet, designed to serve the interests of mankind, is managed by the supercomputer, Grosser. But when Grosser decides to take over the world, a savior is needed! A computer-illiterate girl named Yui Kasuga happens upon software program IR, which recruits her as savior of Comnet and pulls her into the virtual world inside. There, Yui is given the power to become Corrector Yui so that she can fight against Grosser and his evil Corruptors. Inside the virtual world for the first time, Yui must face one of Grosser's henchmen. She must also battle another of Grosser's minions, this time one who's infecting the e-mail passed between Yui and her friends. And finally, Yui and IR suspect foul play when Chef Kirch, a family friend who can never get his recipes quite right, has to face customers who've turned into ravenous zombies! (Source: VIZ Media) — Description from AniList community (anilist.co).