Kouki and Yuuri are stepbrothers. Yuuri has always clung to his older brother while Kouki tries his best to accomodate him without exposing his romantic feelings for Yuuri. Nonetheless, Yuuri realizes his love for Kouki and feared that it would push Kouki away. Then came their father who had left 10 years ago to pursue his photography career. Kouki uses this to run away from Yuuri. It's dramatic and really not well-executed. But long story short, the two has some unrealistically supportive family who let them have their relationship. It's meh.
Kimi wa Boku no Uso