Shun asked him often about his biological father, but Akio answered him Shun is like his biological son. Shun didn't tell him he falls in love with Umi Matsuzaki. He get know about this relationship, when Ryouko Matsuzaki calls him on the phone. Then he tells his son, he should ask Yoshio Onodera.
Yuuichirou Sawamura is a good friend of him. Yuuichirou entrust him and his wife with baby Shun. He often visits Akio to help his family financial.