A message arrives on Himuro's smartphone from his son Yuta, who is now a high school student. Himuro stares at the message with a startled expression. The message is a single word - Revenge. Then, there is a picture of Yuta, gagged and staring resentfully at the lens.  "A school trip to Taiwan... Revenge..."  Himuro assumes that the remnants of the "Black Dragon" who killed Kaku and his friends in Okinawa have kidnapped Yuta to take revenge on him, and immediately decides to go to Taiwan to rescue his son.