Prison Playbook (2017)

Kim Je Hyuk, a famous baseball player, is arrested after using excessive force while chasing a man trying to sexually assault his sister. Shockingly to him and the rest of the nation, he is sentenced to a year in prison. There, he meets his childhood friend and fellow baseball player, Lee Joon Ho, who gave up on baseball after a car accident, but is now a prison guard and one of Je Hyuk's biggest fans. The drama revolves around Je Hyuk's time in prison, as well as the prisoners he meets and the events that take place there. (Source: MyDramaList)