Captain Dan has now been revealed as the long lost Dantetsu Ichimonji (Col. Blackstar)! Colonel Ichimonji swears Dr. Oedo to secrecy about his true identity as Takuma has enough trouble focusing on his pilot training and the fact that the press would have a field day with Ichimonji's sudden return. So, he continues to wear the mask (now safe of Doppler's control). Now that Col. Ichimonji knows Takuma is his son, this does not change the rigorous flight training. In fact, it becomes all the more intense! Col. Ichimonji will not reveal himself to his son until he becomes a man.
