Streaming: Crunchyroll
Episodes: 12
Source: Light Novel
Episode Summary: Mizuto and Yume are new to living under the same roof. After the marriage of their parents, they’re stuck navigating the awkwardness of gaining each-other as new stepsiblings. Unfortunately, their situation is made even more awkward by the fact that the two dated while they were in middle school and then broke up at the end of the school year. While they put on a decent front of getting along with one-another for the sake of their parents, behind the scenes it’s all bickering over who’s the actual older sibling and how annoying they find one-another.
After the two start the new school year and enter high school, it isn’t long before their classmates infer their situation. Some boys think that getting close with Mizuto will somehow get them easy access to Yume, but Yume finds that thought so distasteful that she feigns a brother complex to get them out of her hair. Though the two ended their romantic relationship on poor terms, it seems as though there might still be a faint spark left behind. But how much do the two feel like disrupting their new home life to figure things out for sure?