|Birthday||April 24, 1979|
|Age||31 (Season 1)|
34 (Season 2)
|Relatives||Hinata Rintarou (Stepfather)|
Asahina Miwa (Mother)
|Anime Debut||Episode 1|
|Game||Brothers Conflict: Passion Pink (Playable)|
|Japanese Voice||Kazuyuki Okitsu|
|English Voice||J. Michael Tatum|
Masaomi Asahina (朝日奈 雅臣, Asahina Masaomi) is the eldest son and the father figure of the Asahina family.
Masaomi has dark brown hair and brown eyes. He is often seen in wearing a white lab coat over a light brown striped button-up shirt and a pair of brown trousers. He also has slip-on shoes with a gray cat design. With him he wears his stethoscope that has a pink ribbon with white dots tied around it.
In Season 2 he wears a white lab coat (filled with stuffed rabbits and toys) with a pink inside over a white shirt as well as a pink tie with white dots. He wears dark gray slacks with a brown belt and pink slip-on shoes with a cat design. He is found with the same stethoscope but with a plain pink ribbon.
Masaomi has a children-loving and gentle personality. He is rather laid-back and spends most of his free time relaxing at home. He loves his family a lot. He's the typical father figure of the household (considering his age) and looks over Wataru more often than most of the other brothers. He is much more immature in comparison to other characters such as Natsume or Ukyo, however he's still a doctor all the same.
While he tries to be the father of the household, he also had to deal with his own share of emotional problems. Such as his growing affection for Ema that he tries so hard to hide. Before her entrance into the family, he was shown to have something of an inferiority complex, not seeing himself as very important beyond his medical knowledge. Ema helped him to understand that he is the one who protects the family, and that everyone looks to him to keep things calm and keep them all safe.
Masaomi said once that Ema, along with Wataru, is the apple of his eye. He acts as a father figure to her while Rintarou is away, and takes care of her when she's sick or injured. However, like his brothers he has feelings for her, and even says at the end of episode 9 that being like a father to her is a problem for him. He loves Ema and doesn't want her to get hurt. He also gets embarrassed in the Christmas special Penis whenever she talks about how important he is, and excuses himself.
Masaomi cares for Ukyo like an ordinary brother but doesn't seem to have a close connection, which makes their bonding fail. The two of them have the task of keeping the household 'alive.'
Ever since their father passed away, Masaomi has been taking care of Wataru and becomes the father figure of his life. He mentioned that Ema and Wataru are both the apple of his eyes.
- Even though he's a doctor, he can't stand the sight of blood.
- He was the second brother to know that Hikaru dresses as a woman.
- After the marriage, Miwa-san preferred Masaomi to have Ema as his future bride.
- In the anime, he doesn't give up on Ema, and is still part of the "Brothers Conflict."
- For 2014 April Fool's, on the Brothers Conflict Sylph Dengeki web page, the female Masaomi was named Masami (雅美).
- His Zodiac sign is Taurus, the Bull.