Kentarō Yamanaka is a character from the anime film Nine 2: Koibito Sengen. He is a third-year student and serves as the star pitcher for Bunan High School's baseball team. His position on the team establishes him as a rival to the players at Seishuu High, where the story's main characters attend school.

Regarding his personality and motivations, Kentarō develops a romantic interest in Nakao Yuri, who is the manager of the Seishuu High baseball team. This interest creates a significant love triangle, as it directly conflicts with the feelings of the protagonist, Niimi Katsuya, who also has feelings for Yuri.

In the narrative of Nine 2: Koibito Sengen, Kentarō's role is primarily that of a romantic rival. However, his character receives less focus in this sequel film compared to the first installment. The story's emphasis shifts toward resolving the dynamics between Katsuya, the track athlete Yasuda Yukimi, and Kentarō's own younger brother. Consequently, his prominence as an active rival is reduced in this film, despite his established interest in Yuri.

Key relationships are central to his character. He has a younger brother named Jirō Yamanaka. Jirō joins the Seishuu baseball team during his second year and later develops feelings for Yasuda Yukimi, a track athlete who had previously pursued Katsuya. This connection further intertwines the Yamanaka family with the main circle of students from Seishuu. As for his development and notable abilities, the primary information available highlights his skill as a talented pitcher, which is the foundation of his rivalry with Seishuu High. His personal journey in the sequel is less detailed, with the narrative focus moving away from his romantic pursuit.