Tatsuya is a clone of Terumichi Madoka but was given birth to be his wife Azusa and is therefore considered a son of Terumichi and a sibling of Kiyoko. He is about thirteen years old and can use the Dynamis. He is extremely attached to his sister, as she is the only family he really has, his mother having descended into madness or depression following Twin X. He trusts the Countess more than his sister does, and assimilates with the ORGA very easily, but he sometimes has trouble following the Countess's orders.