He is Chiba Todou's best friend. He fights alongside Todou's on the tennis field as his partner.

On her first day at Nishi High School, 15-year-old Hiromi Oka is inspired by top player Reika "Ochoufujin" Ryuuzaki to take up tennis. Shortly after joining the school's tennis club, she encounters Jin Munakata, the club's new coach. Munakata puts everyone under rigorous training that even puts Ochoufujin to shame. Despite the hardships, Hiromi's determination prompts the coach to select her as part of the club's main players. Because of this, Hiromi must endure the peer pressure from her seniors to become an ace tennis player. 
(Source: Anime News Network)


He's a voice actor affiliated with 81 Produce.

[Profile](https://www.81produce.co.jp/actor_search/index.php/item?id=17)

Three years has passed since the events of the first series. Hiromi continued training with her coach and became Japan's junior champion. Their common profits have also contributed to the coach being chosen as the first trainer of the Japanese Selection of Tennis and is arranged to head a trip with the youngest members of the team to USA. The relation between Hiromi and its trainer is narrower at personal level but it exceeds the teacher-student bond with great difficulty.

High school freshman Hiromi joins the tennis club because of her admiration for Ryuuzaki. Ryuuzaki is a senior, who's the best tennis player on the team and also nicknamed "Ochoufujin", ("Madame Butterfly"), because of her elegance on the tennis court. However, the new coach, Jin Munakata, wants the inexperienced Hiromi to play in a forthcoming tournament. 
Due to this, Hiromi considers quitting tennis for good but, in the depth of her soul, she soon realizes that she loves tennis after all. She returns to the club and, under Munakata's coaching, her talent starts to bloom. 
In the end, Hiromi develops a strong emotional bond with her coach, not knowing that Munakata is risking his life because of a chronic illness. 
(Source: AnimeNfo)

Hiromi continues developing her tennis and shows the results while undergoing an emotional change into an adult.

Yuu Ozaki