The green Verdies are the tiny, but brave guardians of the lakeside. The young Verdies only become guardians when their hair turns brown. Until then, however, life is boring. The youngsters with green hair are not allowed to fly on warblers, not allowed to row alone, and they're not allowed to ride wild frogs at the rodeo. Willy Whistle's big dream is to become a guardian, but his curiosity always gets him into trouble. However, the whole lake becomes at risk when the enemies of the lakeside, the Grimps and the swans, enter into alliance. The guardians are helpless, but Willy comes up with a daring plan in order to save his home and his trapped friend, Jeremiah Jump. Luckily he is not alone, because Grandpa, the water snakes and the frogs also come to his aid.
《幻界王》主要讲述在大多数人天生就拥有“幻魂力”的幻界大陆上，一名天生没有能力的少年从小就梦想成为下一任幻界王。可是，没有半点能力的他能实现自己的梦想吗？在天武考试前的某一天，他遇见了上次大战中落败的魔武的间谍少女。就这样，背负着复兴魔武而潜入天武的间谍少女与梦想单排成王的“零天赋”的青铜少年，将卷入这个幻界大陆中天武和魔武两大势力的各种阴谋和斗争中……
这部《魔胎传》有两集，分别是上集《狂王復活への祈り》和下集《新宿摩天楼大戦 》。有些人说剧情不衔接之前三部曲这是事实，但其实这部的故事设定发生在之前三部曲之间，相当于是补了一作插叙，目的是为创造出“狂王”这个可以对抗超神的力量好让剧情得以延续下去。
