|Debut||(minor antagonist) Syo and Ren's route|
|All Star||(minor antagonist) Ringo's route|
|Music 2||not available|
|Game Debut||Debut, select routes only|
She is the ex-girlfriend of Jinguji Ren and also works as an actress at Shining Agency.
She had long, mid-length, wavy dirty blonde hair, dodger blue eyes and wears mid-thigh sleeveless V-neck, carmine/dark red dress which was wrapped in left side, however appears to be bra-less, revealing her cleavage and her curvaceous figure.
According to Kurosaki Ranmaru, she is the Queen of Scandals, since Seira loves to humiliate people.
Uta no Prince-sama: DebutEdit
Route: Kurusu SyoEdit
She attempts to steal the song from Haruka at the recording studio. She bullies her and tells her she is a complete failure. After Ai and Syo fends her off, Syo has to take punishment so they wont fire Haruka. Syo comforts Haruka and works out their new role Uta no Prince-sama together. The two of them get sent alone to a private island that has a small house with a recording studio in it,so that this is the only way they can record and prevent it from stealing their song.
Route: Jinguji RenEdit
In Ren's route, Ren gets requested as part of the main cast for the upcoming movie, he read through the script and her name was listed there, revealing it was Seira and requested him to practice their acting roles together, much to Ren's dismay. The reason why she choose him, that she loves attractive, young men, who takes their movie main roles with her. She knows Haruka is Ren's girlfriend and threatens her that she is going to steal Ren back, away from her. When Haruka got back home, she opens the T.V. and watch the talk show, she saw Seira being interviewed with and says that she would "fall for the co-stars she was working with", Haruka is getting depressed, when she heard it from her. Some at the time, Ren gives excuses to Haruka, that he is busy, because of Seira she's been forcing him to hang out with her, during their dates, such as going shopping together and taking him to dinner. Haruka happens to catch them on one of their dates and of course gets extremely upset. When Ren manages to catch her she refuses to talk to him until she says she saw the two of them dating.
- At the True Love ending, in the backstage, she gives up and tells Haruka that she accept her defeat so she couldn't break off Haruka's and Ren's relationship, seeing their love is so strong that they have is each other then leaves them be. Haruka watches Ren's main role at the movie and tells him that the love scene was shocking and she’s “jealous a bit”.
Uta no Prince-sama: All StarEdit
Route: Tsukimiya RingoEdit
At the Television studio, Ringo is set to be interviewed with her. Seira tells him that he's been fooling his fans by being a trap and challenges him to do a performance for a debut in his man form. Ringo’s accepted it and says that he will perform at the Shining music festival but in his man form. He agrees to do this but later on realizes that when he’s in man form he can’t be as flamboyant and personable and feels like he has nothing going for him unless he’s a trap. Despite this Haruka encourage and defends Ringo from Seira, that Ringo is gonna put on an awesome show and tells her to back off. Seira just says Ringo’s a loser trap with a secret girlfriend and walks off. At the small empty restaurant, Haruka was going to give Ringo some moral support. When she's been ran into by Seira, Seira tells her that Ringo is her sworn rival/enemy, and she admitted herself that after seeing his acting in his male form, she feels that he should just stay as a guy. On top of this, she’s tells her that if Haruka and Ringo lose the music festival, she will tell everyone that they're dating, Haruka became extremely worried, when she realized about this and then runs away into Ringo the next day in tears.
- In the Love Ending, Ringo’s team wins the music festival and Haruka debuts. Seira admits her defeat and promises not to tell anyone about Ringo and Haruka’s relationship.
- At Kouhai Ending, Ringo’s team wins the music festival and that night Ringo stops by Haruka’s place to celebrate her debut. He grabs her and smooches her on his lap. Ringo then defeated Seira on some show together that they appear on, and then he becomes popular with everyone. He complains that he only wants to be popular with Haruka as he glomps her in his trap form.
- During in the middle of Ren's route, Seira calls him "my boy" and have done everything to make Ren come back to her but in the end, the love of Haruka to Ren still gained victory.
- Seira almost resembles Rangiku Matsumoto from Bleach.
- Her surname, Hoshikage (星影), means starlight.
- She often refers to Mikaze Ai as bouya (ボウヤ), meaning "boy".