My Stepmom's Daughter Is My Ex

継母の連れ子が元カノだった

Mizuto Irido and Yume Ayai dated through junior high and broke up just before starting high school. The next day, their parents announce they are getting married — making the ex-couple step-siblings living under the same roof. Determined to avoid awkwardness, the two agree on a rule: whoever acts like they still have feelings first loses. The contest to stay indifferent proves harder than either expected.