Minato Sahashi (voiced by Shinnosuke Tachibana) is an ordinary candidate. After failing the entrance exam twice in a row, he is determined to launch a third round of attack on his ideal university. Unexpectedly, a girl suddenly appeared and completely changed Minato's ordinary fate. The girl's name is Yui (voiced by Saori Hayami), who calls herself a wagtail, and Minato becomes her Reed Fang in her mouth. It turns out that a vigorous war is now underway in the capital, with a total of 108 wagtails participating in it. They have to make a contract with their master, Reed Fang. Only with the help of Reed Fang can they feather and participate in the battle. In this way, Minato was inexplicably involved in the war. In addition to Yui, other wagtails include Kusano (voiced by Hanazawa Kana), who is small in size but has a big temper, Matsu (voiced by Endo Aya), who is mature and powerful, and Tsukiumi (voiced by Inoue Marina), the unruly sister. Can Minato and his wagtails win in the face of such powerful opponents?