Ashinaga Oji-san no Yukue(1999)

Ashinaga Oji-san no Yukue

Haruhi, who grew up in an orphanage, has five "Ashinaga Uncles" who write to him once a month and help him with his school fees and expenses. Kasuga began to look for them in order to thank them, but somehow ended up living with Natsumi, the caretaker of an apartment building, and his lover Yasuyuhiro....

(Source: Houbunsha, translated)

Note: Dates based on the volume releases.