On November 22, 2010, Japan was targeted by missile strikes, a terrorist act that thankfully did not damage anybody, and became known as "Careless Monday." The incident was quickly forgotten, and society went about its business as usual. Three months later, during her graduation trip to America, amiable college student Saki Morimi's life is drastically transformed when she is saved from unforeseen difficulty by Akira Takizawa. Takizawa is upbeat, but unusual in many ways—he is nude and has amnesia, thinking himself to be a terrorist. He also has a peculiar mobile phone that is filled with 8.2 billion yen in digital currency. Despite Takizawa's questionable characteristics, Saki immediately becomes friends with the mysterious young guy. Unbeknownst to her, this is the start of a dramatic death game involving money, cell phones, and the salvation of the world.