Responses
The prequel is this one: http://www.mangago.zone/read-manga/tsumasaki_ni_kiss/
It's not exactly their story, the thing is that Kyouya appears in this story as side character and his actions are kinda on the bad side for most people. ( ̄へ ̄) I was not his fan when I first read it and I still do not agree with his actions but I think it's just he's TOO intense for his own good. I got that after reading Gravity eyes and even started kinda admiring his stubbornness and strength. ( ̄∇ ̄") Sorry for the long answer but I just can't help myself when it comes to the stories I like ╮( ̄▽ ̄)╭
Rereading is always good when the story is as touching as this one... I must say that apart from his not so good behaviour Kyouya is a really strong person, I read the prequel (actually I have the physical copy) and yes he was an ass but maybe because some stuff hit home I actually feel kinda sympathetic towards him. I'm sorry if some may think I'm ignoring the bad stuff but well I'm way too simple minded and yeah