I Became the Crazy Instructor at the Academy

Rader says:

Setting of this novel is similar to many others. A guy gave up on his life and time to first clear a game but saw ending he abhorred but before he could rant he was sent into game world as the villain who was a tutorial boss but came back as the hidden Final Boss in the game.

So Ivan is a weak character but his noble family is connected with Church. Church here is very corrupted, Goddess they pray to is a direct general of Demon God. Demon God himself is not a bad guy per se but a true God of Destruction as he comes and destroy everything once in a while and Goddess chosen ones pick up the last ambers of the humanity and starts afresh. Anyways Demon God has Seven Masters of Sin who are different guys given powers of sin and are given a chance to be the leaders of the world after disaster and Ivan the Tutorial Boss was actually the one having Gluttony since the beginning. In the game he went into shadow after showing that he was defeated and when Game protag defeated Masters of Sins he absorbed their power and even power of Demon God.

Anyways, Ivan has power of Gluttony. MC possessed him and also got the power of Game protag of seeing status. And he was able to see Ivan another power, Incomplete Omniscient eyes of Demon God. It’s very likely that Original Ivan was created as a vessel for Demon God and he possibly survived till the end but regressed many times as after beating a boss he felt like the world is too real and also felt a Deja Vu.

So this is the setting, a Korean MC liked a game series for which he was unnaturally obsessed over. He was sent in the body of Ivan and there is no game protag. Ivan before possession helped at least one main heroine from a clear death and she is obsessed over him. It is very likely that Before Possession Ivan had a lot of secrets. There is a status screen but no system or such. MC has powers of Ivan, Gluttony which can absorb other Sins and Eyes of Demon God which give him a power to see magic spells clearly. There is no mission or such, MC is just hoping to end the game in body of Ivan and trying to go back to Earth after end of the game as he don’t have any other choice but to see the end of the story and face Demon God.

Honestly, it feels like Original Ivan became absolute being after he absorbed Sins and Demon God and even Game Protag. He absorbed the power of Adam who was game protagonist and was able to Regress due to some plot Armor. Basically OG Ivan most likely took place of OG Game Protag and used game elements to reset the timeline. Maybe he became the MC in Korea and was sent back into the world as Ivan when he finished the game and was able to learn a lot about future events. Game on Earth could be the representative of his own memories of first round or so.