King of Fighters Summoning System

Jiang Xun, a shut-in, accidentally transmigrates to another world. Here, warriors excel at close combat, mages strike hard from afar, and assassins can turn invisible and kill with a single blow. There are also priests known for healing and powerful buffs, as well as summoners who call forth all kinds of mighty monsters. Our protagonist's soul ends up in the body of a useless summoner. Just as he's about to accept his fate, he unexpectedly awakens the King of Fighters Summoning System, which lets him summon characters who have appeared in the King of Fighters games, with a chance of even calling forth some of the ultimate bosses...