Looking for a novel from a few years ago

The world in the novel was composed of several continents, and each continent was the background of an anime. Among them were the Slaying Crimson Pupils, the Legend of the Weapon Race, and the Eaters. At the beginning, he encountered the remonstrance mountain and the underworld, and later on, he would encounter the legendary Rei of the weapon race. In the setting, the world the male protagonist was in was the game world. Players would appear, and later on, they would turn into children and appear in the real world. Just remember these, please tell me the novel title

Answer 1

I can't access the Internet directly to search for information. But if you tell me the name of the novel, I can try my best to help you find relevant resources.