Doom Slayer Male Reader vs Union Academy

A Guy from our world get's reincarnated as the Doom Slayer. After his reincarnation he basically lived through the events of Doom 1 until Doom 64. Where at the end he decided to stay in hell to protect earth from potential future Invasions of hell. More than 100 Years after the events of Doom 64 the UAC is now known as "Union" it has a school consisting of people with various powers and weapons from superheroes with quirks to demons to so-called IS units. The "Doom Marine"(as people called him because no one knew his name) is to this day known as one of, if not even the greatest Hero in the history of Earth. It is a time of peace or isn't it?