Daisuke Nikaido secured the role of ace pitcher for Meisei Academy's junior high baseball team, a position heavily influenced by his father's status as a wealthy alumnus and school benefactor. This preferential treatment sidelined more talented pitchers like Touma Tachibana. During his first year, Daisuke received a diagnosis of a serious heart condition. He concealed it from everyone except his family, his doctor, and team manager Kuroyanagi, continuing to pitch without informing coaches or teammates. Soichiro Tachibana caught for him then, succeeding Tadashi Imagawa in that role. Daisuke anticipated not surviving the required surgery, though his father remained confident in his recovery. The surgery succeeded, granting Daisuke what he called a "new lease on life," after which he chose not to return to baseball in high school.

Looking back, Daisuke voiced no regret over keeping Touma Tachibana from the mound and retaining the ace title. When the full truth of his health and selection emerged, no resentment lingered between him and the Tachibana family. Neither side apologized, but they achieved mutual understanding.

Though no longer playing, Daisuke maintains a consistent, supportive presence for Meisei Academy's baseball team, attending games while managing ongoing health challenges from his past condition.