Junjō Romantica: Who are Nowaki and his Hiro-san?

Kamijou Hiroki is the childhood friend of Usami Akihiko from the main Junjou Romantica series. He was originally in love with Usami, but Usami did not return his feelings. One day, he meets Nowaki in a park when a rocket Nowaki launches nearly hits him, and Nowaki accidentally happens to witness him crying over Usami. Nowaki, who is an orphan that was raised on public charity and a selfless, altruistic individual, has never desired anything in his life - that is, until he meets Hiro-san. The rest, they say, is history.