MTL - Start with Batman - Chapter 6 bat

Two heroes of the game Legend of Heroes 2 who were rotten waters*.

He became a teacher at the best magic academy in the empire.
….For being mistaken for someone else.

Mechanics fix things.Fighters break ‘em.Those were the two truths Perry lived back on Earth. When he got isekai’d into a young noble with newfound magical powers, he found himself stuck with an awful choice. Try to survive on the Front, the mystical battleground where Hydras and Devils roamed free… Or find another way.So he took an oath. An oath that made him a Magus Dominus. A mage lord. He’d escaped his fate, least for the moment.For most his life, Perry was used to being alone. When he got sucked into Ro'an, he was suddenly thrust into the role of surrogate son to his loyal servant and half-brother to a tempestuous Storm mage. With their help, Perry prepared his best to be lord and protector for his domain. And if he fought a few monsters, and helped a few people along the way, well…Mechanics fix things. And fighters break ‘em.-Progression Fantasy with light LitRPG elements-No romance-Kingdom building and magic progression

[Ding! Sorceress Beauty Merlin from Camelot has added you to a chat group full of beautiful maidens!][Ding! You've claimed the title of Supreme Demon Lord!][Ding! Fairy Queen Ophelia tagged you in a post!][Ding! Medusa sent you some of her spicy videos, shut your blinds before watching!][Ding! Your dog has been transformed into the Ancient Black Dragon Veligrpyh!]James Kang, once the youngest heir to the multi-trillion-dollar Hart Global Corporation, has everything anyone could dream of: money, luxury, and freedom. But his life is hollow—friends are fake, family distant, and his days are a blur of shallow extravagance.One late, lonely night, James gets a notification:[Congratulations! You have been added to the Ancient Multiverse Chatroom!]Thinking it's some cringy online role-playing game, he decides to entertain himself and plays along, proclaiming himself the “Supreme Demon Lord.”The group, filled with titles like:[Princess of the Azure Seas][Dragon Emperor of Ashvale][Goblin Slayer Supreme][High Priestess of the Sun][Fafnir, the Pet Wyvern]And they seemed hilariously invested in their roles.What starts as a joke takes a bizarre turn.The more James participates, the more he notices strange phenomena: glowing runes on his skin, magic artifacts materializing from nowhere, an elder dragon in his garage, and a sudden mastery of dark magic.Things escalate when a private group chat, run by a perverted female King Arthur, invites him to [The Table of Beauties], a circle of god-tier roleplayers… or so he thinks.Soon, James learns the truth.The chat is an interdimensional nexus connecting real worlds where magic, legends, and gods exist. His casual banter and fake roleplay have turned him into a living, breathing Demon Lord, complete with a castle in Hell, loyal monster armies, and reality-warping powers.To make matters even crazier, his “friends” start visiting Earth, and they’re nothing like he imagined!