Dogi✩Maji✩Memorium

Doji ⭐Maji⭐Memorium (Doji Maji in short) is an RPG school dating sim where anyone who registers is pulled into the game world. (note: If you die in the game, you die for real). To leave the game you have to win it.

Mammon originally had the idea to register Satan and Lucifer to the game to make them work together in order to get out of it. (Lesson 10)

Leviathan helps Mammon registering them, but since he wanted to play this game for so long, he registered himself as "Leviachan". Then invites MC as well and Mammon follows along (and he's being registered as "Stupidmammon" by Levi).

Setting
The game is set in a fictional school, which seems to be in the human world.

Plot
MC is being registered as the heroine (female, totally not related to MC's gender or appearance) and the other characters have to increase the favorability score with her (like how you raise the intimacy with the brothers).

You can win the game only if the heroine accepts your love on the Roof of Legend.