Upgrade in an Alien Game

The protagonist accidentally traveled through time while playing a stand-alone mini-game! After repeated proofs, he discovered that he could level up in the game! The upgraded strength can be brought back to reality! From being an otaku with less than five combat abilities, to leveling up step by step by fighting monsters, becoming free and carefree, heading into the universe, looking for a real game This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.