If you like to see just actors falling in love on set, you won't get that (jk)
Double is not a BL, it goes further than that, is about how the codependency takara feels for yujin after he "saves him" from the lowest he's been and gives him a new purpose, and about how yujin's quiet resentment fights whatever he might feel for takara, because despite loving him, he accidentally shaped him into a better actor he could ever be. It's a show that will make you feel A LOT, so if you have time, why not giving it a try?

This is a spin-off episode from the show, in its first part we see the main leads' first valentine's day together, the second part is about one of its secondary characters instead.