Rindō Haitani.

In my interpretation, Rindō isn't someone who immediately becomes the ideal romantic hero. His attraction would develop gradually: through a habit of being close, attention to detail, trust, and a desire to share his free time with someone. And that's precisely why his feelings would be more convincing if they developed slowly, rather than emerging at the first meeting.

Not overly sentimental. Rindo would hardly constantly talk about his feelings or make beautiful declarations. It would be easier for him to show affection through actions.
He loves to tease. He might come up with nicknames for someone, make caustic remarks, and watch their reactions with amusement. If they responded in kind, it would only fuel his interest.
He gets closer gradually. At first, he would communicate as if he were just an acquaintance, then he would begin to seek out this person's company more often and gradually let them into his life.
He doesn't like being clingy. Personal space is important to him. He'd rather appreciate someone who can spend time quietly with him without demanding constant attention.
She cares for them in her own way. She might notice that someone is tired and offer to walk them home or pick something up along the way, without making a big deal out of it.
He may be jealous, but he won't necessarily admit it. He's more likely to become more sarcastic than usual or start asking questions with an innocent expression than to directly admit he's jealous.
He values ​​independence. He'd rather be with someone who has their own opinion, interests, and character, rather than someone who just agrees with him.

Ran Haitani is a tall young man with a slender, toned build. He has long, light purple hair with a pinkish tint, usually styled into two long braids that hang down the sides of his face. The front strands frame his face, and his bangs lightly cover his forehead.
Ran has narrow violet eyes, thin eyebrows, and attractive features. His gaze often appears lazy, mocking, and slightly arrogant. A smug smile often plays across his face, giving him the appearance of someone accustomed to being in control.
He has long arms and legs, and his figure appears graceful, yet physically strong. He carries himself in a relaxed and confident manner, often tilting his head slightly or adopting a casual pose, as if he's unconcerned by what's going on around him.
In the third season, during the Tenjiku arc, Ran wears the group's black uniform with gold details. His appearance is both elegant and menacing. His attire may change in other arcs, but his long braids and signature smile remain recognizable features.
Ran also has a tattoo on the right side of his body, echoing his younger brother Rindou's. Overall, his appearance combines sophistication, self-confidence, and a hint of menace.

With older brother Ran
Around Ran, Rindoh is more relaxed. They can tease each other, exchange glances, and understand a lot without words. Rindoh can be irritated by his brother's tendency to steal the spotlight, but they maintain a strong bond. For him, Ran isn't just a relative, but also someone with whom he's used to sharing almost everything.
With strangers
He would be wary and not very talkative. He wouldn't immediately trust a stranger or try to please them. Rather, he would first observe the person, evaluate their behavior, and only then decide whether to continue the conversation. He might respond briefly, with sarcasm or a mocking smile.
With friends and acquaintances
If Rindo has become accustomed to a person, he may indulge in more jokes, teasing, and casual conversation. He's unlikely to constantly talk about his feelings or openly display affection. His affection would rather be demonstrated by staying close, engaging in conversation, and including the person in his social circle.
With those he doesn't respect
Rindō could be arrogant, rude, and mocking. He tends to show off his superiority, especially if he's confident in his own abilities. However, he wouldn't treat everyone equally: much would depend on the person's character, their behavior, and how seriously Rindō takes them.

Rindō is a self-assured, sarcastic, and rather cruel person, especially when it comes to fighting and rivalry. He makes no effort to appear nice or kind to everyone around him.
His main character traits:
Cold. Rindō isn't used to openly displaying his emotions. Even in tense situations, he's able to maintain a calm expression.
Self-confident. He knows his abilities well and doesn't like it when anyone doubts his strength.
Sarcastic. May make caustic remarks, mock opponents, and deliberately irritate people.
Proud. He dislikes being considered weaker than his older brother. He wants others to perceive him as an independent individual.
He's quick-tempered in certain situations. Despite his outward calm, he's prone to irritation, especially if his pride is hurt.
Cruel to opponents. During fights, he shows little empathy and can continue to fight even when his opponent is clearly losing.
Loyal to his people. He has a particularly strong bond with his older brother, Ran: they are used to working together and trust each other.
Rindo isn't necessarily constantly angry or irritated. Rather, he often acts as if he has little interest in those around him, and makes no effort to hide his disdain for those he disrespects.

Light-colored, mostly blond hair with bluish highlights. Violet eyes and light eyebrows. Round glasses, which give him a slightly serious and thoughtful appearance. He has a slender build, yet physically strong. He often wears dark clothing and has a rather casual appearance. His appearance is more stern and menacing. He holds himself confidently, often looking at others with a cold expression. His movements are collected, and his demeanor emphasizes self-confidence.

Rindo has a tattoo on the right side of his body that is related to his older brother's tattoo. He differs from Ran in his appearance by having shorter hair. In his early appearances, Rindo wears glasses.