A new pathogen "K-55" was stolen from the University Institute of Medical Science. In addition, an email saying "I demand a ransom of 300 million yen for all citizens as hostages" arrives to the director of the research institute. The remaining time is 4 days. However, it is a biological weapon made in secret, so it can't be reported to the police. The criminal, Kuzuhara, died in a traffic accident immediately after sending an email, and the only clues are the receiver of Kuzuhara's belongings and seven photos of the teddy bear left on the digital camera.
Kazuyuki Kuribayashi, the head of the research institute, who was confronted with an impossible task from Masaomi Togo, the director, to find out the ski resort in the photo and collect the "K-55" as soon as possible, went to Satozawa Onsen Ski Resort with his son Hideto, who deduced the whereabouts of the teddy bear from the Heading to. However, my skiing skills are so bad that I'm disgusted by my son Hideto. There was someone who secretly aimed at such a chestnut forest.