if i remember correctly, the protagonist was originally from earth but transmigrated into some servant of a mage academy. like the dark magic branch of the academy i think, with necromancy and stuff. raising skeletons from the ground and what not. the mc was there for a few years (original body, before mc transmigrated) but the entire time he was there, he was basically tortured and abused by the students of the necromancy/dark magic department. eventually, i think the mc finds some sort of book in his little shed/home? it's some kinda typical cheat that gives him some overpowered ability stuff, i can't remember what. anyway, mc makes his own skeleton but it's different from the others. also, iirc, the mc hides his abilities for a while so no one knows he actually has gotten stronger. that's about all i can remember. if anyone knows, thnx in advance.