Although Kyosuke is attending Honan High and is shown taking part in last year’s competitions, he’s not a member of the Honan Stride Club in the anime beginning.
It is later revealed that Kyosuke left the club after the “KGB Incident”, a beating occurred after a competition against Tsubakimichi High School in which Kyosuke was believed to have kicked Heath’s already injured leg and knocked off other members out of rage.
This isn’t what actually happened though, and the truth is only shared between Heath, Kyosuke and the other present members (all third-years of the time, apart from Tomoe) until Heath reveals it to his teammates in episode 5.
[The third-year relationer of the time was accusing Heath of faking his injury and refused to recognize that he was the one who caused it, having been tricked by the other team’s relationer and then pushed his teammates to run too fast to the point of collision. Tomoe, who had heard everything, insisted that it was his fault. The third-year relationer then kicked Heath’s leg and was immediately knocked down by Kyosuke. When Hozumi (who grows to hate Kyosuke from this moment) and the others arrived, he was the only one standing and was then accused. He didn’t defend himself and took all the blame instead in order to save the Club. It is said that if all the people involved had confessed the club might have been shut down.]
After the truth has come to light, Kyosuke is asked to join Honan Stride Club again in order to substitute for Ayumu, who has been injured, and he accepts.