Just Die Alone (1992)

Ken has been chasing after his ex-boyfriend, who he lost touch with after he was transferred to Southeast Asia, but his sadness at not being able to see him again leads him to have an impromptu relationship with a local man who asks him out. Three years have passed since then. One day, while living with his new partner, Masashi, Ken noticed something strange about his body and wonders if his body might have been infected with HIV...