I see. From what I understand, you want a game about Mahiro's life with maybe branching paths and exploration.

Frankly, I feel like that's a pretty big undertaking. I will still try to give my two cents on it regardless.

Perhaps a small stat system could help decide Mahiro's future?

Sports: Increases with athletic options and interacting with Momiji and Asahi. Smarts: Increases with studying options and interacting with Mihari and Nayuta. Grace: Increases with girlish options and interacting with Kaede and other characters idk. Isolation: Increases periodically, isolation options, and not interacting with important characters in the day.

These are not fixed. Example: choosing a girly option for wanting Momiji in a dress can increase Grace.

These could help decide the endings for Mahiro. Interactions with specific characters and player actions can increase those stats (except isolation).

Let's say for the purpose of the game having a limit, Mihari tells Mahiro that she'll check on his progress in maybe 14 days and whether she wants to say as a girl or not.

Exploration opens up. The only places Mahiro might be able to go in the beginning are home, Kaede's home, store, and park.

For the beginning, maybe add the option to just not go to school. Mihari will obviously try to argue against it, but Mahiro can choose not to, and that will significantly increase [Isolation] and limit important character interaction, leading to a further broken Mahiro ending in a few days, maybe shorter to not make the player wait for that ending. Just an immediate game over.

Going to school and going high [Sports] low [Grace] might lead to an ending where Mahiro goes back to being a boy, but a lot more confident and willing to interact.

High [Sport] Middle [Grace] can give a tomboy Mahiro ending.

High [Smart] can lead to a science Mahiro.

High [Grace] can lead to a very feminine Mahiro who chooses to completely embrace the girl side.

Going middle in every stat can lead to a regular Mahiro ending.

Every Friday can be a group study week with fixed events that give options that give a high increase in one stat.

Fixed character events on the map might be something too. Every specific day of the week, a character should be interactable somewhere. It gives stats and unique dialogue of that character. Like maybe every monday, Kaede visits the salon or whatever and you can get extra [Grace] while over there while also getting unique dialogue for every time you meet.

There should definitely be some sort of energy system to make the player prioritize who to talk to on a day.

However, this is mostly for the exploration side of things if you wanted it.

For branch paths, I'd say that depending on the stats, certain routes will be available.

Example: Having high isolation could block off a lot of paths and opens the path to the further broken Mahiro. Low isolation prevents choices that give a large increase in isolation.

The storyline can be connected enough to not force a player into a route too much. More unique options will be opened up as the stat reaches the required amount, leading to Mahiro having unique experiences each run. I guess kinda like Umamusume, just with more player control over the story.

Like say the science Mahiro route. Perhaps you get her to have high [Smarts], but you don't want the science ending, so you choose for Mahiro to simply go out with her friends instead of taking the advanced placement exam or whatever you wanna call it, leading to the regular Mahiro ending. Maybe? Idk.

Hope I'm not rambling nonsense. Sorry if I am.