Kōyō Ozaki carries herself with grace and poise, embodying a dignified yet menacing presence befitting a Port Mafia executive. However, beneath her composed exterior lies a deeply cynical and jaded worldview. Her failed attempt to escape the Port Mafia has left her disillusioned with concepts like hope and love. Kōyō believes that those born into darkness are fated to remain there, unable to seek the light without encountering despair. She often uses floral metaphors to express her philosophies, likening people to flowers that wilt when exposed to the harsh realities of life. In her view, purity and innocence are fleeting, and there is a certain inevitability to corruption.

Among her peers in the mafia, Kōyō displays a more relaxed demeanor, enjoying leisure moments and camaraderie, particularly with Mori Ōgai and other executives. However, with those she distrusts, like Ace, her passive-aggressive tendencies become apparent. Despite her elegance, Kōyō is fiercely ruthless and unrestrained in combat, unleashing her violent tendencies when necessary. Her attacks are calculated but brutal, and she often spares no mercy, with the exception of Kyōka Izumi, for whom she maintains a protective restraint.

Kōyō’s relationship with Kyōka reveals a more complex side to her personality. As Kyōka’s mentor, she instilled in her a bleak mindset, convincing her that she was irredeemable and responsible for her parents’ deaths. This manipulation was an attempt to keep Kyōka tethered to the mafia, projecting her own despair onto her protégé. Despite her harsh treatment, Kōyō genuinely cares for Kyōka, often intervening to protect her, even after Kyōka defects to the Armed Detective Agency. Kōyō’s attachment to Kyōka drives her to extremes, such as intercepting a Special Division transport to reveal the truth about Kyōka’s past. Over time, and with influence from Osamu Dazai, Kōyō begins to release her grip on Kyōka, allowing her to grow and find her own path.

Despite her outward confidence, Kōyō harbors vulnerabilities, particularly her fear of Osamu Dazai’s infamous methods of interrogation. This fear highlights her human side, contrasting with her otherwise fearsome reputation. While she begrudgingly shows humor and leniency toward those connected to Kyōka, Kōyō remains a steadfast and formidable figure whose loyalty to the Port Mafia is unwavering.

Kōyō Ozaki is a tall and slender woman with striking cherry-red eyes (depicted as violet in the manga) and light scarlet hair styled in a traditional Japanese bun. Her hair is adorned with elegant accessories, including three golden kanzashi (reduced to two in the anime), a light pink furry clip, and a red ribbon that forms a five-petal flower. These details contribute to her refined and graceful appearance.

Her makeup includes red eyeshadow and light pink lipstick, complementing her polished look, along with red-painted nails. Kōyō’s attire features a black-and-pink kimono with a pattern of red spider lilies, paired with a maroon obi (sash) that showcases bellflower patterns (changed to a maze-like pattern in the anime). She completes her outfit with a mantle that transitions from dark pink at the bottom to lighter shades above, and she wears brown lace heels (depicted as simple brown shoes in the anime). The anime adaptation also added floral designs to her mantle.

In a specific instance, Kōyō disguises herself as a postman to infiltrate and attack a Special Division for Unusual Powers’ transport vehicle, showcasing her versatility and dedication to her missions.

In her youth, Kōyō attempted to leave the Port Mafia with a man she deeply admired. Unfortunately, their plan was thwarted, and the man was killed as punishment. This traumatic event left Kōyō deeply scarred and instilled in her a lasting grudge—though her anger was directed solely at the former Mafia leader who committed these atrocities.

When Ōgai Mori assumed leadership of the Mafia, Kōyō’s role within the organization evolved. Around a year into Mori’s tenure, she was assigned to oversee Chūya Nakahara following his recruitment into the Mafia. Initially, Kōyō felt exasperated by the responsibility, finding herself too young to be addressed as “ane-san” (姐さん, meaning “elder sister”) by Chūya. However, as time passed, she grew to accept the title, especially as she matured and developed a deeper sense of camaraderie within the Mafia.

Kōyō’s ability, Golden Demon (金色夜叉, Konjiki Yasha), allows her to summon and control a sword-wielding phantom. Similar to Kyōka Izumi’s ability, Demon Snow, Golden Demon is an externalized ability that manifests as a powerful and imposing spirit. However, unlike Kyōka, Kōyō has complete control over her phantom without the need for intermediaries, such as a mobile phone, allowing her to wield it directly through her own will.

Golden Demon demonstrates incredible destructive power and is a testament to Kōyō’s mastery over her ability, which solidifies her position as one of the Port Mafia’s most formidable executives.

As an executive, Kōyō commands significant authority within the Port Mafia, overseeing missions and ensuring the organization’s dominance in Yokohama. Her strategic mind and combat prowess make her a key player in the mafia’s operations.

Kōyō’s relationship with Kyōka is central to her character arc. She views Kyōka as a surrogate daughter and strives to guide her, though her efforts are often at odds with Kyōka’s desire to leave the mafia. Their bond highlights Kōyō’s protective instincts and her longing to preserve Kyōka’s innocence despite their circumstances.

Kōyō’s ability, Golden Demon, makes her one of the most dangerous fighters in the series. Her precise control and strategic use of her ability allow her to dominate in battle while maintaining her characteristic grace and composure.

Kōyō Ozaki represents themes of loyalty, strength, and elegance in Bungo Stray Dogs. As a powerful executive of the Port Mafia, she exemplifies the organization’s ruthlessness while showcasing moments of compassion and introspection. Her bond with Kyōka Izumi and her mastery of Golden Demon highlight her complexity, making her one of the most captivating characters in the series.