Takao Kiyosato serves as the vice director of Kiyosato Hospital. A decade before the depicted events, he performed surgery on Shuji's father, whose death resulted from that operation. This event drove Shuji to enter medicine and investigate his father's demise. Takao is married to Misako Kiyosato, who was previously Shuji's romantic interest. Shuji's discovery of Misako's marriage to Takao, combined with his suspicions regarding his father's death, fuels his plan for revenge against Takao. This revenge specifically focuses on undermining Takao's relationship with Misako. Takao Kiyosato is also the son-in-law of Kouichirou Kiyosato, the director of Kiyosato Hospital.