Doukyuusei (NAKAMURA Asumiko)
Kusakabe thinks Sajou considers music to be beneath him--the one subject where Kusakabe excels. But one day after school, he discovers Sajou alone in their classroom practicing for an upcoming concert and offers to help. After a series of regular meet-ups, Kusakabe develops feelings for Sajou and kisses him. What follows is a story of firsts. This is a sweet love story, a bit sad at points, but ultimately happy. Doukyuusei was made into an anime, which is absolutely lovely and follows the manga to a T. The voice actors did a fantastic job. It also has two sequels and a side story, which I tagged "Doukyuusei" so you can find them.
Sotsugyousei
The sequel to Doukyuusei, in which Sajou and Kusakabe have to face their upcoming graduation.
Sora To Hara
I can't believe I'd skipped over this. Now "Occupation to Beloved" makes a LOT more sense! I loved the cameo with Sajou and Kusakabe, and I while I didn't really like Hara in Doukyuusei, I felt a lot for him in this story.
blanc
As their relationship continues to mature, Sajou realizes he can no longer envision his future and asks for some time apart from Kusakabe, who then revokes the privilege of calling him by his first name. If you love these two, you might want to wait for this to be completed or at least get a few more chapters in, because I feel like I've been betrayed. ETA:
Occupation To Beloved