I've just finished uploading the first demo of this game. My best guess as to it's approximate playtime is maybe ten minutes?
The bulk of the gameplay here is in school, and the interactions with the students in Terada's class which will eventually make up for the VN-like elements in the game, with a bit of combat near the demo's end. I feel like I've mentioned this before, but, there is certainly inspiration taken from Memories Neverlasting, and the ability for players to choose who to interact with in the context of a "day". The choice of "how" to interact with said characters is currently limited to whither or not to talk to them, however.
The demo leaves off at a point where the game would likely set itself into a story-loop of school, followed by dungeon. As for optional content to possibly break that up, I've never been particularly good about coming up with that kind of stuff. Then again, not having them might just be my personal preference as a player. I think on the gaming diary thread, and I generally forgo optional content. Off the top my my head, the exception to this general rule is obtaining the 108 Bonus of Destiny in a Suikoden game. If I can think of other exceptions, I might note them in a later comment.
As for what might yet come, I'm not sure how much longer this project will be on hiatus. Though, it might be a more accurate representation of this game's development to say that I maybe do one small thing (usually writing), then close MZ and/or Open Office. I have no idea what the next demo would consist of, or when it might come down. I wanna say that the next demo could be up to Boss Fight #2, and give players a better sense of what the game loop would look like?