My Stepmom's Daughter is My Ex Episode 1: The Former Couple Refuses to Say... "It`s Things Like This...!"
Episode 1 of 12 of My Stepmom's Daughter is My Ex, aired July 6, 2022, 24 minutes. Available with English subtitles and dub where released.
Episode summary
Mizuto and Yume used to date, but now they've suddenly become stepsiblings. Both of them agree that they don't want to do anything that'd disappoint their newly remarried parents. However, neither of them can accept the other as being the eldest sibling in the relationship. So they both agree to settle the matter with a game. Whoever does something in conflict with what people might consider normal sibling behavior, loses. Making them the younger sibling.