Amiboshi, known as Kōtoku Bu, is a Seiryū Celestial Warrior born under the star Neck in Tenryō, San'un Province of the Kutō Empire. He is the elder twin brother of Suboshi. As a Celestial Warrior, Amiboshi can emit chi through his mouth and channel it via a flute to control others' wills. A skilled flutist, he holds his instrument to the left when using his powers but to the right when playing normally. Working as a spy, he is initially tranquil and reserved but can become single-minded and merciless.
Before Miaka's arrival in The Universe of Four Gods, Amiboshi was a kind young man dedicated to protecting his younger brother. He first appears disguised as Chiriko on Nakago's orders. When discovered, he falls into a river and is presumed dead. Found by an old couple, he pretends to have amnesia and is adopted as their son, named Kaika. Later, he saves Miaka during her search for the Shinzahō but pretends not to recognize her. As the story unfolds, he struggles between aiding the Suzaku and Seiryū Celestial Warriors.
To save Amiboshi’s life, Suboshi gives him a forgetfulness potion through a kiss after Amiboshi nearly dies trying to protect his future. Losing his memory forever, Amiboshi avoids sharing the same fate as the other Seiryū warriors and becomes the sole surviving member of the Seiryū Celestial Warriors. When Suboshi dies in Miaka's world while following Tamahome, Amiboshi feels like a part of him has disappeared. However, he later corrects himself, saying it felt more like a part of him had returned.
