Utakata no omoi (1999)

Koizumi, once a high school P.E. teacher, recognized Shizuo's exceptional talent for long-distance running and dreamed of training him into an international athlete. Over years of guidance, Koizumi developed feelings that went beyond the teacher-student boundary. Years after graduation, they reunite in Tokyo, begin living together, and resume training. Shizuo confesses that he has loved Koizumi since high school, and they finally become partners. Yet as Shizuo pushes himself to meet Koizumi's expectations, recurring chest pain begins to threaten both his athletic future and their fragile happiness.