As the movie starts, we see the little Mai, but regular Mai can't see her. The conversation that Mai has regarding her mother is interesting. On one hand, we do know that the stuff that happened in middle school isn't something that she can't gloss over and forgive her so easily. Seeing how much the child actor and her mom are together does give Mai a what if feeling. Any person shouldn't go about living without their mother, which is one of the central themes of this movie. Plus we know from Dreaming Girl how Mai's mom is when Mai dies. Makes me wonder if after seeing Sakuta facing his mom again, will Mai do the same?
Rio's comments of little Mai gives the same logic when there were two of herself and when we had the two Shokos. Basically, the two can't observe each other. Although we did recall Sakuta able to get his past self to observe him in Dreaming Girl. So maybe it is possible. The other part is the new mark on Sakuta's body. The curious point is what did it appear. Was it about Mai's mother showing up to her graduation and that got him thinking about his own mother for a moment?
The next portion focuses on Kaede, which finalizes her arc. After if one remembers their mom ended up how she did because of the situation with Kaede being bullied. So you can imagine how big of an event this is. Kaede feeling responsible for how her mom broke down. While their mom blaming herself for not being there for Kaede. Which gives the immense heartwarming scene of what seems them being a family. Of course, as the movie plays out, that is not immediately the case.
When Sakuta arrives at school he is invisible, which is the situation Mai was in during the Bunny Girl Senpai arc. Recalling Mai was conflicted in that she didn't want to be noticed, but also wanted to restart her Showbiz career. For him, the way he was nervous heading back to his parents' home was a hint towards the issue. When reading his mom's diary he finds out he doesn't exist in her eyes. Though he recalls that he never made eye contact with his mother. The way this seems to connect is that for Kaede's sake, he had to cut his mom out of his life emotionally. He had to be independent and what seemed like leaving his mom to his father. Although in all the scenes in the series we can clearly tell their father was also doing his best to assist Sakuta with Kaede. Though barely any mention of his mother. So now with puberty syndrome kicking now as Sakuta tried to be invisible to his mother, now everyone else can't see him. This is the main thing he needs to solve.
This leads back to little Mai. In this movie, at least her presence in the story is to guide Sakuta who is lost. Now where he ends up is in another universe and that is where the bullying incident for Kaede never escalated. The 4 of them are one happy family. This feels immensely ideal. Though what is interesting is Sakuta's conversations with his mom is interesting because it is clear Sakuta wasn't this considerate when he was younger. Though it feels like nothing is different besides the 4 of them are family. It could be easy for Sakuta to live in this ideal world, but remember how everyone tackled their own problems, it would feel wrong if he ran away from his problems.
This leads back to the universe where Sakuta still feels invisible. This now draws parallels to the Bunny Girl Senpai arc where Mai remembers Sakuta. The Marriage paper is the equivalent to the study session in that arc. I do think if they took a bit more time to add things from her perspective and her suddenly remembering Sakuta would have elevated the moment, but it is still a good scene. Though him talking about his problems with Mai is a great scene for the first part, this is where Mai wants to be and that is to be there when Sakuta needs her the most. As she points out Sakuta had to become an adult and honestly had to be independent. Which is a great thing, but we know he cut emotional ties to his mother. To know she is getting healthy again means her coming back into his life. Which begs the question of what does he want. He knows he has to have to face it, which is hard.
The scene in the hospital was outstanding because it was Sakuta finally facing his mother. He looks at her and realizes how hard she worked. At the same token, the mom acknowledges how hard Sakuta worked. All the efforts helping Kaede going through her issues get acknowledged. There was a point he wondered if losing the old Kaede made things meaningless, but their mom saying she is proud of him for being a great brother acknowledges that this wasn't time wasted. A great emotional scene between these two & Kaede that now the 4 of them are truly a family and Sakuta finally opening up to his mother for the first time in this series.
Shoko is still around and as we recall from Dreaming Girl, both her and Sakuta remember lots of the events that were now considered a dream. Mai doesn't even remember Shoko. Though given she remembers everything that goes on, the series implies she is a key. So Toko Kirishima's music doesn't exist in any instance. But who is Toko Kirishima?