Wataru Minakami is sent away from home to Promised Island to attend high school there. He falls off the ferry and almost drowns, but he's saved by a girl who calls him "Big Brother!"
As Wataru gets used to life in the mansion, many mysteries await him. There's a blistering-hot kimchi gratin no one remembers cooking. Then, he encounters a monster out in the woods! And finally... he meets even more sisters of his!
