Yoite is tall in height, and slender in weight for his age. He has a ghostly pale complexion, though that can be attributed to his poor health, and his hands are scorched black due to his Kira abuse (he wears beige gloves over them to hide it). He naturally dons a beige cap over his hair, usually giving him the appearance of swept bangs over his forehead, a light brown turtleneck shirt, and a long black trench coat reaching below mid-thigh.
Yoite uses the Iga's kinjutsushō "Kira". "Kira" can control the ki of the one it pierces by halting the flow of ki in the target's body, causing their bones to break or their body to completely explode. But conversely, it is capable of activating ki as well, as seen with his revival of Gau from his comatose state. The cost of using this technique is the loss of the user's ki or life force, gradually losing their five senses. With this, it is seen that Yoite's sense of taste and hearing decaying rapidly, and is the cause of his sickly health and scorched skin.
Yoite's mother had intended for him to be named Sora (そら) if he had been a girl. While he seems to have gone by that name for a while, he never considered himself to actually be Sora, since he's not a girl.
He is intersex, and although he is referred to as male in anime and manga, he lived his life unsure of who he really was. His mother died in childbirth, and his remaining family considered him an 'angel of death' for that reason. He was confined to the basement and his half-brother Tsukasa Kōdō (香道司, Tsukasa Kōdō) was forbidden to approach him.
When Yoite turned fourteen, his family decided to kill him, slashing his throat and unsuccessfully attempting to force Tsukasa to do the same. After this desperate attempt of ending his life, being erased from existence became his goal. He ran from the house and was saved by Hattori, who accepted him into the Grey Wolves. Yoite spends a year studying the Kira technique and all required ninja skills. Hattori promises this would bring him closer to his goal of being erased. His desire to disappear comes from his painful past and his fear of death. By disappearing he wouldn't have experienced so much pain nor death. Yoite is then placed under Yukimi's care and is given the name "Yoite".
Yoite first meets Miharu when retrieving Fuuma's kinjutsushō. The two slowly form a bond after Yoite blackmails Miharu into promising to use the Shinra Banshou to fulfill Yoite's wish. In turn, Yoite promises to make Miharu the ruler of Nabari. As their bond deepens, he becomes more protective of Miharu and begins to show rebellious signs toward Grey Wolf leader, Hattori, when Miharu is in harm's way by his orders. Yoite becomes openly rebellious when Hattori attempts to persuade Miharu to not grant Yoite's wish, causing Hattori to send Kasa assassins after Yoite and Miharu. Yoite goes berserk after killing Hattori and causing the Iga Village to be destroyed by the Shinra Banshou.
Shortly before Yoite dies, he realizes that he was alive all along, because he had Miharu and Yukimi there for him. He expresses his happiness that he was not alone in this world, and tells Miharu that he is fully satisfied simply being the "Yoite" that Miharu and Yukimi knew. He then again asks Miharu to erase him - not for his sake, but so that Miharu won't succumb to sadness over Yoite's death, and can continue smiling. After mentioning his desire to return to Yukimi's home (reminiscent of the time when he left Yukimi's home with only a "bye", which Yukimi replied: "isn't it 'see you later'?" - Yoite now finally sees Yukimi's home as his home). He asks for Miharu to make some more okonimiyaki, so he could leave, and during that time Yoite dies, happy and satisfied in Miharu's arms before the Shinra Banshou could be used.
The Shinra Banshou notes that, though Miharu's wish came too late, his desire still came true. Though it is unknown exactly what Miharu's wish was, no one can remember Yoite. Therefore it seems clear he was erased to some extent (especially since the scar he gave Miharu is gone). However, since the characters themselves or the events they are faced with do not seem altered, it is unclear how well he was erased. Yukimi (雪見和彦 Yukimi Kazuhiko) and Miharu also recall that someone close to them is gone, and express extreme loneliness over it - though they cannot remember who it was, and what was erased.
- Yoite's original name was meant to be Sora Koudou. Upon attaining guardianship from Yukimi he covered himself behind an emotionless shell, failing to talk and eat. Yoite never mentioned his real name, so Yukimi half-heartedly named him "Yoite".
- Yoite has a half-brother named Tsukasa.
- Yoite has similarity of Newtype Mobile Armor, Alpha Azieru Because Yoite goes berserk with his Kira while the Alpha Azieru uses Funnels and Beam Finger Hands for All Range Attacks (Killing any enemy).
- Yoite could no longer taste food nor hear very well due to his depleting life force by using the Kira technique, though he seems to eat feverishly when given the chance.