Kukun is a young man with a lean figure. He has light brown hair with the lower half shaved, while the upper half is worn in dreadlocks. He is almost always seen wearing yellow sunglasses that cover his brown eyes. He wears a pink short sleeved jacket over a yellow shirt as well as jeans covering his knees. He also has a few tattoos on his body including concentric circles on the back of his hand, letters on his fingers that write 'butterfly, and a few other tattoos on the back of his neck.
Kukun seems mild mannered and easygoing. He likes to express himself through fast-paced rapping. During one such time he expresses his anxieties about how to present himself to people as well as stand out. He often felt invisible as no one even inside his gang seems to notice him. Because of this, he has several self-doubts about himself, to the point of finding a kindred spirit in the equally socially hindered Miko. Kukun also expresses interest in flower language.
Mayuta had inherited his crippled father's job of removing labels and caps from packages to recycle them in Yamanote. Because of his poor upbringing, he was unable to attend major schooling. He eventually joined Wamu's Gang and gained the moniker Kukun.
While he transports the labels and caps, he often passes by Miko's residence. He watches her water her snapdragons, as well as witnesses the strange whimpering noises, unaware that they are also Miko's. When he first approaches her, she mostly ignores him, thinking he just wants to use her to get close to Miki Makimura. However, he denies this, and soon realizes Miko's name is Miki as well.
The next time they meet, he confronts her about the whimpering, but she snaps back at him. In response, he breaks out into a heartfelt rap about how he feels invisible and inferior among his friends. It was a rap about Miko, not just himself, used to express that he understands her much more than she initially believed. She realizes this quickly and begins to shed tears in response, causing Kukun to worry he had upset her.
He takes her to his home, where they exchange words about their lives. When Miko tells him she feels she will always live in Miki Makimura's shadow, he tells her she is wrong, and that he believes she is smart, hardworking, and cute.
The two later attend a Sabbath party, where Kukun asks Miko to dance. She accepts, but the two are soon attacked by a demon, leading to Miko's transformation into a Devilman and Kukun's death. It is safe to assume that Miko may have killed Kukun as during sex she has a tendency to kill her partners. A spider to a butterfly.
It is unclear exactly how Kukun dies. Shortly after the Sabbath party his friends lose all contact with him, and in a later episode his severed, tattooed fingers are shown lying on the ground. In the ninth episode you see Kukuns sunglasses fall out of Miko's purse and his friend the one in the hoodie recognizes them. This is why he turns against the other's.