Nanako Sumirekawa (voiced by Yukino Satsuki) is a 13-year-old talented writer. One day, she came to Hong Kong to attend a book signing event, but unexpectedly encountered a terrorist attack. Under the protection of tour guides Michelle (voiced by Shoko Kikuchi) and Maggie (voiced by Hiromi Hirata), Nanako was lucky to save her life. However, the incident did not end there. Nanako and her group discovered that this seemingly accidental terrorist attack was actually aimed at Nanako. At the same time, Nanako also received a threatening letter, in which the person predicted that he would attack Nanako's book signing event and vowed to let Nanako die in Hong Kong. Michelle, Maggie and their sister Ani (voiced by Chiwa Saito) became Nanako's protectors. While protecting Nanako, the three also had to find out who was the real murderer behind the scenes and what their real purpose was.