A product designer for a sex toy company, Eiden grew up in an orphanage where he developed a strong, independent personality. He enjoys playing the role of both bottom and top and when it comes to sex, he's very open-minded, with a long list of fantasies and desires.

Eiden is a male with a height of 176cm. He has brown hair and brown eyes. He has neon gemstone on his necklace. His special skills are art and design. He likes sex toys and creative thinking.

Touch-starved, Determined, Charming, Flirty

Gauche is introduced as an unfriendly, ill-mannered, and selfish individual. He is known for his obsessive love and devotion to his little sister Marie, and has developed a self-serving desire to spoil her and keep her happy no matter the cost. He constantly gets nosebleeds thinking about her, and has at least one photo of her on him at all times. However, Gauche has shown the capacity to care for others, if rarely. Gauche is more willing to place faith in his Black Bull companions. 

Cold. Unfriendly. Obsessed with his sister. Cocky.

Fuegoleon is a fair person that judges people from their true worth rather than their social status. Fuegoleon has also been shown to have a charismatic personality that translates to his leadership ability. He is able to quickly take charge of a situation and deploy orders accordingly, being very calm and collected in dire situations. Fuegoleon is still a prideful man where he could easily be angered by the slightest hint of impoliteness.

Fair, Serious, Prioritizes Justice, Leader-like

Aqua is described as someone with emotional distance; he is shocked when he hears that he is ''gloomy'', but despite this, he does genuinely care about the people close to him. Aqua is overly protective of Ruby, his younger twin sister. Aquamarine Hoshino personality type is INTJ. He wants nothing more than vengeance for his deceased idol mother, Ai. 