What's it called?
LOL maybe I jumped the gun on asking this question. I believe you were revering to this manga but if I'm wrong please correct me. (￣∇￣")
Although Hitorijime Boyfriend is the prequel, it only has 1 vol, while Kousuke x Setagawa (Hitorijime My Hero) have 5 vol. My hero even in top 20 of most popular BL rank poll in 2013-2014
http://www.mangago.zone/read-manga/hitorijime_boyfriend/
It's this one. The two mcs in the hero story are only background characters in this one, but I still liked them more than the mcs from hitorojime boyfriend.
I'll be brutally honest when I say, I read the original story and was "meh" for most of it. I was, however weirdly invested in the background characters and hoping they had a series of their own, and, low and behold, not only do they have their own story, but it is getting an anime too! Glad I wasn't the only one thinking they liked the best friend and older brother pairing better.