Hamura Shou, winner of the national kendo championship, is transferred to an only boys private school. He there thinks he meets his lost younger twin brother Kai, who strongly denies this. Strange things happen at the school somehow referring to a magical world called Winfield. After re-encountering his best friend Naoto and while meeting many new friends, which each have specific abilities, he soon discovers his own inheritance and the difficult tasks ahead.

川越春间（平川大辅 配音）是一名十分平凡的男子大学生，因为童年时代的不幸遭遇，春间对兄妹之间的亲情十分渴望。一年圣诞节，春间向圣诞老人许愿希望能够得到一个妹妹，让春间再也没有想到的是，自己的愿望竟然成真的，一个名为裘可（斋藤桃子 配音）被送到了春间的身边，成为了他的妹妹，就这样，在春间居住的椿庄里，裘可和春间开始了他们的同居生活。 因为平凡的外貌而常常产生自卑感的管理员芹川千岁（水桥香织 配音）、大大咧咧个性奔放在生活里邋里邋遢的美女足来真琴（森永理科 配音）、经营着花店性格十分温柔体贴的老板娘圆崎绫乃（大原沙耶香 配音），和生活在椿庄周边的朋友们，春间的日常拉开了序幕。