This is a story about a boy named Tannaka Yuki, one fine day a new student joins their class and for some reason is interested in Yuki, her name is Sasaki Naomi. She takes him to a place behind his school and they find something really weird there. What was it that they found there? Who exactly is Sasaki Naomi? How does she know about this? All these questions will be answered in 1608: Case