Uncle is Tatsuki Kawamura's legal guardian. When Misaki is introduced into Tatsuki's life, Uncle is seen anticipating this event. He prepares and encourages Tatsuki to embrace Misaki and his role as a Dragon. Tatsuki doesn't question this at first, but later demands to know everything Uncle has kept hidden from him and if his being a Dragon has anything to do with his parents' death.
Uncle is reserved and patient, unlike Misaki who is quick to act and frustrated by Tatsuki's intentions to not pursue the legacy of his bloodlines.