From koyukiya:

Hasegawa Yuiji accidentally finds out that his classmate, Yoshinaga Yamato, is gay. Eventually, he realises Yamato’s gaze is directed towards an unattainable love. From a study group together Yuiji finds out that Yamato is a “pretty nice guy,” and despite his awkwardness, starts wishing for his happiness...

Two boys from different schools have developed a routine where Ren, the elder of the two, assists the younger Nachi in fixing his necktie before they board the morning train for school. When Ren begins to worry that they may be giving the public a wrongful impression of their relationship, he realizes that he does indeed possess romantic feelings for Nachi and decides to put some distance between them before things go any further. But is that what Nachi really wants?

Yutaka gets his yearly letter from his beloved older brother.
(Source: MIAB)