Hiromi Yoshino is Asuka's father, who Asuka had quite good memories with in his childhood, especially in baking. He confessed to his wife, Kiyomi Masamune, to that he always wished to be a girl, and left the family, rumored to later has turned into a transvestite. Years later, Yoshino came back, taking care of his son and protecting him in secret. He opened a pastry shop in the same town, selling a variety of feminine-designed pastries, each one with a theme, which Asuka and his friends visit quite often. He has a younger sister, Miyuki Yoshino, who is an expert reporter and photographer.
Hiromi left his house, telling Asuka's mother that he always wanted to be a woman.
Hiromi always appears to help his son from the shadows.
First, when Asuka and Tonomine are disguised as samurai he saves their identities being revealed. Later on, it is revealed that he has set his friend (who is his sister's ex-boyfriend,and currently works as a teacher at Asuka's school) to keep an eye on his son and help him when he is troubled.
When Asuka's mother returns with the goal to make all otomen dissappear Asuka is troubled since he cant even be himself at home. At that point Hiromi makes up the plan of a special course "cooking for men" giving shelter to his son. Asuka's mom panics when she suspects her son is an otomen bursting into the cooking lessons and destroying the kitchen by accident. After her suspicions are (falsy) cleared she invites Hirome to live
at their house for awhile. There Asuka and his Father start spending even more time together. During that period, Asuka gets caught trying to protect Hiromi from yakuza thugs though he fails to do so and gets caught. Hiromi running to his son's resque ends up revealing his identity to protect Asuka. When the situation is resolved without revealing anything to his ex-wife he leaves the house in good terms with his son and the promise to meet again. When he leaves Asuka calls him "dad" for the first time.
Later it is revealed that Hiromi is living together with his sister ex-boyfriend. It can be pressumed they have a romantic relationship (since when Asuka asks his teacher why his dad didnt become a woman, he replies with "i cant tell you that we aren't even dating) although the truth is never revealed.
In the end the mystery of him remaining a man is solved, as his wife states that he was too scared to change after leaving his family. His dream comes true in the end as he appears in a female form in his son's wedding.