High schoolers Mizuho and Wataru are going on a kendo club trip, but because nobody apart from them can go, Wataru decides to invite his younger twin brother Kakeru as well. He decides to go with a woman called Ayumi who is in love with him. Once they arrive at the hotel, they discover a virus inside of it. To make matters worse, the hotel keeper Kamishiro-san and his ten year old daughter Koyuki both have it and are insane, but they can't leave because there is a big snow storm outside...

Akino Minori returns to her hometown after her parents went abroad due to work. She was supposed to live with her grandparents, but they are on a long trip, so she starts living with her uncle, Kouta. She meets her childhood friends Yuu and Mizuho. Her romantic life now begins.