Kensuke Midorikawa, known as Ken Midori in some versions, is a character introduced as a participant in the local tournament where the main protagonist also competes. His background is marked by frequent relocation due to his parents' work-related travels. Because he never had the opportunity to stay in one school for a long period, he struggled to form lasting friendships and often felt isolated. This history of loneliness is the primary driver for his initially eccentric behavior and his deep desire for genuine connection.

Kensuke has a very distinct personality that is layered and initially misleading. On the surface, he often appears intimidating and eccentric. However, this is a facade born of shyness, as he is revealed to be a very soft-spoken, sensitive, and nervous individual who gets flustered under pressure. To cope with his social anxiety and express his true feelings, Kensuke uses a unique method of ventriloquism with two dog sock puppets that he wears on his hands. The blue puppet, named Keru, has a sharp-toothed, scary expression and speaks in an aggressive, outspoken manner. The brown puppet, named Besu, has a more approachable look with floppy ears and speaks with a kinder, gentler tone. Through these two puppets, Kensuke can portray different spectrums of his emotions, making it difficult for others to discern his true thoughts. Over the course of the story, he demonstrates significant personal development, gradually becoming more confident and assertive, and eventually learning to speak using his real voice without the aid of his puppets.

Kensuke's role in the story is that of a friend and rival. His primary motivation is to find belonging and build meaningful friendships through the shared activity of beyblading. His key relationships are central to his character arc. Valt Aoi is arguably the most important person in his life, as Valt actively befriended him and invited him to join the Beyblade Club, with Kensuke even stating that Valt was probably the first real friend he has ever had. He also forms a close bond with Ben Azuki, who invited him to join a team called Team Beasts, and Ben’s influence is implied to have helped Kensuke become more confident. He holds a high level of respect for Shu Kurenai, who was the first person Kensuke spoke to without using his puppets. However, this friendship is tested when Shu, while under a different identity, rips Besu, causing Kensuke great devastation. Fortunately, Kensuke holds no ill will after Shu returns to his old self, showing his forgiving and loyal nature. His relationship with Daigo Kurogami began with suspicion but grew into a solid friendship with Daigo showing concern for him.

Kensuke is a talented ventriloquist, a skill he uses constantly, even during battles. As a blader, he is quiet but enthusiastic and is known for being a reliable and supportive friend. His primary beyblade is Kerbeus K2 Limited Press, a defense-type beyblade. His battling style focuses on defense, with his beyblade's performance tip designed to disperse damage from opponent attacks before launching a counter-attack.