Kuroe's manga / #Tragedy(18)

I love mc and Jeeho, but I really don't like Sanho's older sister. I guess it runs in the family to get physical first and talk afterwards. It was wrong when Sanho punched mc extremely hard to the point of knocking some of his teeth out just because he is 'pissed' mc learned he is dating Jeeho. Same thing with his older sister, in chapter 12 she just slaps Jeeho without the full context and then has the audacity to explain tell him to explain. Even worse, in chapter 13 she leaves them stranded in an unknown area while she has all their stuff inside her car. Seriously, what is wrong with these siblings...