What if kotori and maki were stepsister?
Kotori parents had a divorce due to kotori dad had cheat on his wife and had child custody of kotori
Where maki parents also had a divorce due to saw his husband had a affair with a nurse and had custody of maki due to being the next heir to the Nishikino hospital
After that where and go the same bar due to their spouse divorce both of them and that feel heartbroken to them, that they`re sit right next each other this where recognize who did surgery on her daughter. They`re talk what happen to after kotori surgery, she feel better now and now they talk about their divorce because of both of their spouse had cheat and a affair. This where ask her out on a date and she say yes both were very happy about it.
After 2 weeks of dating this where tell her that he had a daughter name maki which is one year younger than kotori and she say to him to visit him and maki, where he say aright. Where bring kotori to Nishikino household where they`re to do introduce together and this where they tell their daughters that they are going to get marry however this kotori happy that have a new dad and little sister, and maki was not happy about it get a new mom and a big sister, the parents them to play at maki room where maki bring a toy piano started to sing aishiteru ban zai and kotori also being to sing with maki. After week that they`re start to bound like sisters.
And after a few day of they parents had got married and kotori tell maki that she had two best friends honoka and umi, where they visit manjuu shop who own by honoka`s family, when they're arrival and go inside the shop, where they were greet by honoka and umi, and they notice someone new, this where maki introduce herself to honoka and umi, they are that she was daughter of and tell them that their parents got divorce and got re-marry again, and after that they start to play tag, and this where maki started to open up to people, and few minutes later of playing tag where honoka ask maki to be they're friends and she agree with it. However this change a chain of events
After many years later maki was a friendly person to people that she know and at otonokizaka high school where honoka ask her to started school idol and she argue to save their school from closing the school, and maki was also a founding member of muse with honoka, kotori, and umi this they start to perforce star dash at the audition. Later rin drag hanayo to school rooftop where they join and afterward the third year girl join as well.