|Anime debut||Episode 11|
|Manga debut||Chapter 27|
|English Voice||Kalob Martinez|
Kusano was one of the parasites who were responsible for the deaths of Kuramori's wife and their daughter. Along with Maesawa and Hikawa, they suspected that Reiko Tamura was a traitor and tried to kill her.
He had short black hair, with an average height and build. He was seen wearing gray dress pants along with a black pin striped vest and a gray long sleeved shirt. In the manga, he appears to have a small scar above his left eye.
He trusted his instinct that Tamura Reiko was not one of their comrades. He was fine with killing his own comrade, if it meant getting rid of Reiko. It's noted that he later begins showing impressive signs of expressing anger.
Kusano is first seen driving Gotou around the corner from a building where the Yakuza were holding a meeting. He comments on Gotou's appearance when he returns and drives off. They return to their headquarters and inform Hirokawa of their success and informs Gotou of Reiko's maternity leave.
Following the death of a parasite that's killed by Shinichi Izumi, he begins to suspect Reiko Tamura who seems to be defending Shinichi despite his danger towards them. When their group assigned someone to annihilate Shiro Kuramori, but failed as they only managed to kill his family. Tamura warns them to not underestimate the human race, however due to this statement his doubts toward Tamura increased. Later that night, along with Maesawa and Hikawa, they finally decide to kill her.
Kusano along with Hikawa and Maesawa, emit strong signals of animosity, luring Reiko to their position. After trading words, with Reiko comparing him to Mr. A and commending them for deciding to kill her, and Kusano informing her that Gotou and Hirokawa know nothing of their plans, Reiko makes her escape. While chasing her down, he decides that it's okay for people to see them as long as they kill her. Sensing that Reiko split herself in two, Kusano follows the section containing her human portion into the city. After witnessing Reiko's recklessness of leaving her body and her apparently irrational behavior towards a human couple, and sensing the death of one of his comrades, he leaves.
At the construction site, he begins attacking Hikawa, who is having her body destroyed from the inside. He claims that he can't be sure who's in control, due to her trying to get close to him. As Hikawa begs for her life, he mocks her, slowly dismembering her body. After killing her, his body is slashed into three pieces, by the body attached portion of Reiko, who had snuck up while he was focused on her detached portion. Trying one last time to kill her, he is easily knocked away and begins to die. Reiko leaves him with a quick explanation of her deceptive strategy and he shrivels up and dies.
Abilities & Powers
As a parasite, Kusano has the basic abilities to shapeshift his head, and maximize the physical potential of the body he's controlling. He can harden his cells for offensive and defensive purposes.