So I guess this ended up just being a two part series? Kinda wanted her mom to piss off. Like did she just leave that house and never go back and Saki's mom just accepted her and she lived with her lol?
Well in the actual series Mutsumi still lives at home, so I think that's why they didn't have her move in with Sakiko. Also Sakiko's living situation in the series is complicated, I'll comment on that below.
Also this was SOOO AGNSTY my god I still think it's a weird age to put them at for this kind of story. Ain't no like ten year olds acting like this lol.
I think the author wanted to set this at a time when Sakiko's family situation was happy, partly to contrast how things are in the anime. Plus with fiction you can write anything and real world logic doesn't have to apply, and I think this works for the series and how the characters are very dramatic prodigies in general.
To get into Sakiko's home situation in the anime, spoilers head, Sakiko's mom in series died from illness, and her dad worked for Sakiko's grandfather (mom's dad) until he was used as a scapegoat for problems at the company, which ruined the career and life of Sakiko's father. From there Sakiko's father becomes alcoholic and abusive. Sakiko also constantly has to get her dad from the local police station's drunk tank, walking him home. So Sakiko in present day doesn't have the home life that she has in this doujin.
This was so close to just being a flat out psycho obsessive horror shesh.
This is in line with a lot of the themes and tone of the actual Ave Mujica anime.
Oh well happy ending for them two at least in this. Because no way her mom that's stuck in the limelight would ever actually just act like her daughter doesn't exist when she flat out uses her to make her career better.
Getting into more anime spoilers but for Mutsumi and her mom this time. In the anime Mutsumi's mom often treats her like she doesn't exist. There's a scene in the anime where the mom says to the band that they can practice in a room in their home that nobody uses. It's a room that Mutsumi is in alone most of the time when she's home, so her mom flat out ignores Mutsumi and acts like she doesn't exist. Also yes in canon Mutsumi's mother says her daughter is a "monster".