- Belligerent Sexual Tension: With Kouji.
- Dark and Troubled Past: Just what made him be the way he is? Witnessing her mother killing her dad and then being scarred by her with the killing weapon, you know.
- Expy: He is what Kojiro Hyuuga from Captain Tsubasa would've been, if CT was a Yaoi (genre) series.
- Oblivious to Love
- Scars Are Forever: Has one on his hip. His mother gave it to him in her Yandere phase, right after she killed her cheating husband.
- Troubled, but Cute
- Belligerent Sexual Tension: With Izumi.
- Broken Ace: He's handsome, smart, good at kendo, excellent in singing and songwriting. And a BUNDLE of issues.
- Crazy Jealous Guy
- Forgotten First Meeting: Kouji met Izumi once during their childhood and fell in Love at First Sight... but, Kouji thought Izumi was a girl and only realized it when they met face to face and he recognizes Izumi in the present.
- Friend to All Living Things: He loves animals, specially dogs.
- Idol Singer
- If It's You, It's Okay: Izumi is the only guy he would ever fall for.
- Long-Haired Pretty Boy
- Love at First Sight: Towards Izumi.
- Love Makes You Crazy
- Love Martyr: At one point Kouji cuts off his own left arm so that his family will leave Izumi alone. And it took Izumi quite a long time for him to warm up to Kouji.
- Mad Love
- Stalker With a Crush
- Stalking Is Love: Izumi not only eventually stops minding Kouji's persistent stalking but says it's why he's falling for him.
- White Hair, Black Heart: Kouji definitely occupies the lighter end of the trope. While he doesn't destroy planets with meteors or burn down orphanages, he's certainly one Yandere of a Seme with some serious shades of Love Makes You Crazy/Evil. Just ask Zarla.
Izumi's motherThe matriarch of the Izumi family, a beautiful woman with a totally broken psyche. She has spent several years in jail after killing her husband and wounding her eldest son.
- Broken Bird
- Driven to Suicide: After being released from jail, Mrs. Izumi meets up with Takuto, explains her reasons to do what she did... and then kills herself.
- If I Can't Have You...: She killed her husband for cheating on her.
- Love Makes You Crazy
- The Ophelia
Voiced by: Kumiko NishiharaThe second Izumi child and only daughter. A remarkably sweet young girl whom Izumi adores.
- Beware the Quiet Ones
- The Cutie
- Happily Adopted: She and Yugo were taken in by a kind couple. They're still in contact with Izumi and care for him deeply
- What the Hell, Hero?: When Izumi collapses due to illness, she gets pissed at Kouji.
Voiced by: Etsuko NishimotoThe "runt" of the Izumis, a very cute little kid.
Ryuuichirou Nanjou and AyakoKouji's father Ryuuichirou is the leader of a very powerful, rich and influential clan, and his main priority is the clan's very famous kendo dojo. Kouji's mom Ayako was a famous actress and model, as well as and one of his lovers.
- Disappeared Dad: Ryuuichirou dies in Bronze.
- May–December Romance: Ryuuichirou was much older than Ayako
- The Mistress: Ayako
- Parental Favoritism: Ryuuichirou favors Kouji over his other sons. That does NOT bode well.
- Teen Pregnancy: She had Kouji as a teenager, but the physical/mental consequences left her unable to raise him properly. Her manager took care of him until a three-year-old Kouji was brought to the Nanjous.
Hirose NanjouEldest son of the Nanjou family, and the one who handles the family business.
- Four Eyes, Zero Soul
- The Dutiful Son: One of the coldest versions ever. One of the reasons why he doesn't get along with Kouji is because Kouji is better in everything but still refuses to follow the family traditions, while Hirose has struggled all of his life to be the perfect son and heir.
- Manipulative Bastard
- Mighty Whitey and Mellow Yellow: Genderflipped with him and his American first wife. They got hitched when he was studying abroads, but they got divorced when he returned home. He then married the very Japanese Kaoruko, who'd give birth to Tatsuomi.
Voiced by: Masami KikuchiThe second son of the Nanjous. He absolutely LOATHES Kouji with all of his soul, and adores the ground Hirose walks on.
- Big Brother Worship: To Hirose
- Mommy Issues and Oedipus Complex: His beloved mother was forced to leave the Nanjou family when little Kouji was taken in by their dad. That's why he loathes Kouji so much.
- The Unfavorite: To really emphasize this at their father's will-reading Hirose is left with the family business and Kouji get the family estate. What does Akihito get? An advisory role under Hirose at the company.
Nadeshiko NanjouThe only daughter of the Nanjous.
- Cute Bruiser: Already training to become a kendoka.
Minako SasakiA cute girl who, at some point, goes out with Izumi. That makes Kouji mad with jealousy.
- The Beard: Kouji accuses her of being this to Izumi after raping her out of jealousy
- Fangirl: Of Izumi.
- Rape as Drama: Poor girl gets raped by Kouji.
Voiced by: Kappei YamaguchiKouji's manager and best friend. his father is the owner of Kouji's recording company.
- Because You Were Nice to Me: Subverted: the person Kouji was nice to was the dying Madoka, as he visited her in her last days. Katsumi became Kouji's manager to show him gratitude.
- Only Sane Man
Madoka ShibuyaA young girl whom Kouji once befriended. She was Shibuya's sister, and Kouji's kindness to her before she died sealed their friendship
Eri Iijima and Kunihide KasayaKasaya is one of Izumi's teammates, Eri is his girlfriend. Hirose uses them both to get back at Kouji
- Even Evil Has Standards: Kasaya willingly goes along with Hirose's plan for Izumi, thinking the latter is going to be tortured by Hirose. But when Kasaya realizes that Hirose arranged a rape for Izumi, he tries to intervene to stop it. It doesn't work.
- Fangirl: Eri, for Kouji. She went Yandere after Kouji announces his retirement.
- Loony Fan: Eri.
- Yandere: Eri doesn't take the news to Kouji's retirement announcement very well and tries to stab him to death.