Kiriya Ubuyashiki (
Kiriya has light, pale skin and large eyes. He has the same hairstyle as the rest of his siblings; a blunt bob with a fringe covering his eyebrows, colored black. As he was raised as a girl, he takes on a more feminine appearance during his first appearance.
During the Final Selection test, Kiriya wears a purple kimono with patterned flowers and a green obi. His head is adorned with a wisteria headpiece.
Later on in the manga, after he becomes the leader of the Demon Slayer Corps, he wears a black kimono with a long white haori that's reminiscent of his father.
During his first appearance in the series during the Final Selection test, Kiriya portrays himself to be polite, competent, and somewhat emotionally detached having calmly and politely greeted the trainees in sync with his sister, professionally explaining the details regarding the test. He is somewhat unfazed when Genya Shinazugawa roughly manhandles of his sister.
Later, upon his father, mother and sisters' deaths, Kiriya shows an entirely different side to himself, displaying his capabilities as a leader. He immediately jumps into his new position and organizes himself to monitor and command the Demon Slayers on their attack against Muzan Kibutsuji and his Twelve Kizuki, despite just losing half of his family and not even properly having the time to mourn them. He shows more mental fortitude and emotional strength in comparison to his younger sisters, who momentarily broke into tears in grief.
However, once his plan results in the slaughter of many Demon Slayers, Kiriya breaks under stress and stops giving orders, much to his sisters' dismay. He is able to pull himself back together after Kanata slaps him.
Kiriya was born to Kagaya Ubuyashiki and Amane Ubuyashiki as their third child and only son of five children. He was born after his two older twin sisters and before his two younger twin sisters. As the sole son of the family, he becomes the male heir, the next head of the Ubuyashiki family and the first in line to inherit his father's position as commander of the Demon Slayer Corps.
From the time he was born, his parents raised him up as a girl because he was weak and frail.
Over a century after Muzan's defeat, Kiriya is still alive and the oldest living person in Japan. This achievement caused him to be interviewed by a reporter, although he remained unresponsive due to his elderly age. The fact he lived so long is proof that the illness which previously cursed their family is now gone along with Muzan.
- Leadership Skills: Much like his father, Kiriya displays advanced skills in leading and commanding an army into battle despite his young age. He is able to immediately take command of the Demon Slayer Corps's command structure and assist the Hashira as logistical support, guiding them into battle.
- Intuition: Similar to his father and his ancestors, Kiriya has a high, almost prophetic intuition, being able to make accurate guesses and hypotheses that were often proven right through feeling alone.
- Extraordinary Memory: Kiriya has shown extremely good memory. He and his sisters are able to map out and memorize the nearly constantly changing Infinity Castle, creating accurate maps to navigate and guide the Hashira through it in real-time.
- Longevity: Due to their relative, Muzan, becoming the first Demon, men within the Ubuyashiki family were cursed with a mysterious illness, causing them to usually die in their thirties. However, after Muzan's death, the curse was seemingly lifted. In fact, Kiriya was blessed with a unusually long life, still being alive over a hundred years later and currently being the oldest living person in Japan.
- Kiriya shares the same Japanese and English voice actresses with Madoka Kaname from Madoka Magica.