The boss (the goddess) didn’t know about the final boss’ struggles

After (possibly) dying from overwork, the protagonist, Jiro Hasegawa, found himself reincarnated as a dungeon monster in another world. Through sheer effort and continuous evolution, he eventually rose to the position of the final boss, entrusted with guarding the deepest part of the dungeon.

Even though he kept working hard, one day, his boss—the goddess—suddenly deemed him too costly to maintain and attempted to transfer him to another dungeon… or so he thought. Instead, he got fired.

However, the place he ended up in was Earth.

Taking on a human form, Jiro found that time had barely progressed on Earth. And so, he decided to enjoy the continuation of his previous life.

Anyway, time to enjoy my retirement life!~