Koto Shinazugawa

Koto Shinazugawa (こと) was the youngest brother of Sanemi and Genya Shinazugawa.

Appearance
Koto was a young boy of light skin complexion. His short dark hair was shaved all over and he had large round blue eyes. He bore a resemblance to his mother and his brother Genya

Koto wore a simple dark brown kimono.

History
Koto was the youngest child of Shizu and Kyogo Shinazugawa. He had six older siblings, with Sanemi and Genya being the two oldest. His father was extremely abusive and often lashed out at his family, though Koto was always protected by his mother. Eventually, his father was killed in a stabbing.

One night, as Koto, Sumi, Hiroshi, Teiko, and Shuya slept, Sanemi and Genya became concerned that their mother had not come home, leading Sanemi to go out and look for her. Genya stayed behind to watch his siblings, who by now had woken up to wait as well. Koto remained asleep in Genya's arms as he attempted to ease his siblings concerns, asking them to go back to bed.

Suddenly, a loud knock rang rang from the front door, which woke up Koto and led Shuya, Sumi, Hiroshi, and Teiko to believe that their mother had come home. Despite Genya's warning against opening it, the door broken open. Shizu, who had transformed into a demon, killed the four instantly before lunging towards Genya and Koto, slitting the young child's throat as she rushed past him. Despite Genya's efforts, Koto died shortly afterwards.

Swordsmith Village Arc
In his battle against Upper Rank Four Hantengu, Genya found the main demon controlling the emotion manifestations but failed to cut through its neck. In disbelief, he realized that the manifestation of anger had appeared behind him. Unable to dodge its attack, Genya's life flashed before his eyes and he reminisced on his childhood and the deaths of his siblings and mother.

Sunrise Countdown Arc
Following the final battle with Muzan Kibutsuji, Sanemi lost consciousness from his sustained injuries and found himself in the afterlife, where he saw Koto in heaven with his fallen siblings.

Trivia

 * Koto's given name means "matter" (こと) in Hiragana.
 * Koto's surname Shinazugawa contains the kanji for "immortality, eternal life" (不死) and "river, stream" (川).

Reference
Кото Шинадзугава