The color of my heart (1999)

High school student Tadashi harbors feelings for his best friend Kota, only to face ridicule from classmates—and growing distance from Kota himself. One day, he encounters Hiroki and Shinji, a same-sex couple on the train, and is drawn to their quiet confidence in being themselves. Curious and captivated, Tadashi begins to follow them, gradually becoming part of their lives. But as their connection deepens, an unexpected incident changes everything.