Itoshi no Mirai-kun

Hibiya Kimita has been friends and neighbors with the naive Shin Mirai since they were both kids. He is mildly amused when Mirai agrees to go out with an upperclassman despite having no experience with same-sex relationships. However, Hibiya sees no harm in his friend dating their senior because Mirai is stupidly straightforward—he is happiest when he is making others happy.

Over time, Hibiya's views on Mirai's love life change, as the other boy repeatedly gets together with men who happen to confess to him. Hibiya has his doubts about the good intentions of strangers, but perhaps Mirai's perspective—though different from his own—is no less valid.