Subaru Sumeragi is the main protagonist of the Tokyo Babylon.
In X, he is a supporting protagonist and one of seven Dragons of Heaven. Subaru's fate in the battle of end of the world has differed.
He is voiced by Kappei Yamaguchi, who also voices Ranma Saotome and Inuyasha for Tokyo Babylon OVA, Shouta Aoi for Tokyo Babylon 2021 in the Japanese version, and Ben Fairman for Tokyo Babylon OVA, and Dave Wittenberg for X TV series, who also voices Kakashi Hatake and Henry Wong in the English version.
In Tokyo Babylon, Subaru was about 16 years old. He had straight black hair that fell to his ears and very green eyes. He wore very extravagant outfits, all designed and made by his twin sister, Hokuto. When he was 9 years old, due to his meeting with the Sakurazukamori, Subaru started to wear gloves enchanted by his grandmother at all times. He continuously wears them right up until the end of the Tokyo Babylon manga. His hands are scarred with the mark of the Sakurazukamori, an inverted pentagram, and the gloves are magicked to cover the marks from anyone with magical powers. After the death of his sister, Subaru's dress style toned down, wearing clothes more suited to comfort than fashion. Subaru also has a ceremonial outfit, a long white tunic with deep sleeves and a pentagram on the back. It is worn with traditional tabi and includes a set of ceremonial beads.
In X/1999, Subaru has grown into a 25 year old adult. His hair is shorter, and has lost the adorable babyness to his features. He's tall and thin, usually seen wearing a simple black shirt and black jeans under a long white coat and boots. Sometimes he wears the gloves he wore as a child but he isn't seen wearing them as often as he did as a teenager. After Seishiro's death, Subaru starts to dress all in black, clothes that fit his new status as the Sakurazukamori and he also grows his hair out a bit more until it's similar to how it was in Tokyo Babylon (this only happens in the manga).
Subaru's main virtue is his kindness. As a young child, innocent as he was, he did not feel any fear when Seishirou Sakurazuka told him that under every Cherry Blossom tree was a human corpse and that the tree leeched the blood, which was the cause of the pale pink color of its flowers. Instead, he felt worried about the person under the tree and wondered if that person felt any pain. He was very close to his sister Hokuto; they suffered a lot when they were separated because of Subaru's training, but lived very happy times together, even when the girl was extravagant and outgoing, while Subaru was quite bashful, yet cheerful. His kindness and innocence were broken when his beloved Seishirou brutally killed Hokuto. After coming out from the catatonia the betrayal caused him, he became obsessed with the idea of avenging her death, turning cold, full of sorrow, but still sympathetic. Upon meeting Kamui, with whom he shared a similar story due to the death of Kotori at the hands of Fuma, he became close to him, and was the main reason he followed the Seven Seals, as he didn't have any interest on the fate of the world.
- In xxxHolic, Yuuko Ichihara mentions knowing an Onmyoji with a twin sister whom she has known since the onmyoji was very young. She hopes that the boy will be happy, but there are many definitions for happiness. The Onmyoji turns out be Subaru, as explained in the extra pages at the end of the book.