Spoiler!
Jihyun isn't really a murderer, it will be proven later in the manhwa. Both guys, Jihyun and Kyujin are good people. It's just that Kyujin is gentle and Jihyun is aggresive and really obsessed with Chiwoo. Eitherway,
i like candies
Comment by incendious hakarii on Back to School - Chapter 4
it's up to you if you love Jihyun more than Kyujin, or vice versa. We (need to) respect everyone's opinion. Just don't fight in the comments, that's so childish ;-;