My Stepmom's Daughter Is My Ex

A boy and a girl started dating in middle school. They were lovey-dovey at first, but due to a misunderstanding over something trivial, they started feeling more frustration than excitement... In the end, they broke up when they graduated. However, Mizuto Irido and Yume Ayai meet again in a surprising way before they start high school. "Obviously I'm the older brother here." "Obviously I'm the...