My Stepmom's Daughter is my Ex Volume 4

A former boyfriend and girlfriend must live uner one roof after their parents get married!"That is... a promise from the past..."A seating rearrangement in class brings the ex-couple closer together...!? Mizuto was elated about changing seats and being freed from his malicious ex-girlfriend seated behind! But memories of a certain good luck charm the ex-boyfriend once shared with Yume resurface...? The intensely-sweet and tantalizing romantic comedy about the bickering ex-couple continues!