The Sotsugyou (Graduation) universe is more complicated than it seems and is quite vast with all the spin-off and derived products.
This single have been considered as VGM for a decade, but i can't relate it to a product.
The Manga was released in 1996
The PSX game was released in 1998
The OAV was released in 1999
I think the Sotsugyou M Franchise was created for the Radio program called Sotsugyou Cross World (not 100% sure for this)
If someone that can read Japanese want to dig further in the franchise,
there's an official website.