改编自月夜泪创作的同名小说，作品背景设定在一个有魔法，有异族的异世界。只不过这并不是一部穿越男主的故事，而是关于一位少年复仇的故事。
故事的舞台在现代的东京。在这个世界中魔法使的存在被认为是很普通的事情。只要通过正式的办理手续，谁都可以成为拥有魔法的魔法使。虽然如此，但它和我们所住的世界还是没什么区别的。电视、移动电话、电脑这些东西也都有，汽车也是靠汽油开动的.为了营造画面真实感，片中的场景就像建筑广告，而熙来攘往的人群、电车，都与现实世界无二
TV动画『IDOLiSH7 -偶像星愿-』2期制作决定！制作公司依旧是TROYCA！十二位偶像的故事再度展开！
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.
