[Rule-based horror + a yandere heroine + power fantasy + cute pets (cute only to the heroine) + infinite worlds]
The top player in a survival game falls into the Dark Realm overnight and becomes one of the lowest-ranking horrors. After contracting a strange pet, she awakens powerful supernatural abilities, throws the instances into chaos, and draws the enforcers' punishment with her wanton nature.
When she becomes a player again, she no longer follows the rules. Her strange pets are her most loyal henchmen, while horrors become food to satisfy her murderous urges. Faced with absolute overwhelming strength, rules are no longer shackles, merely black words on white paper.
Years later, countless rule-based instances have been destroyed by one person's hand. The horrors cling to the enforcers' legs and weep bitterly: “Send this scourge back to the survival game! Our tiny Dark Realm temple can't contain a Buddha this mighty!”
The mysterious beings of the survival game slam the door shut: “You picked up that horror yourself. Now get on your knees and take care of it!”