I Killed the Player of the Academy

Being a character of your favorite game is great! Sure, he’s just a minor NPC, but Corin knows this game like the back of his hand. With his knowledge and the main player Sihu’s abilities, everything’s going smoothly - until Corin discovers Sihu’s been murdering innocent NPCs and stealing their items. Horrified but powerless to stop him, Corin awaits the end of the game - only for Sihu to mysteriously fail at the last mission. Instantly, Corin travels three years back in time. Now, he’s determined to kill Sihu and take on his role - defeat the final boss and save the world. Source: Webtoon