tl;dr: Game made of funny noodle code made by funny noodle man.
Genuinely, anyone who wants to make a game- ESPECIALLY in Unity- would benefit from playing this game. This game is a perfect object lesson in making a ton of beginner-level mistakes and iterating on them before you've checked your work.
This game truly needs no introduction.
The idea of taking out the various rivals and immersing in the Yandere trope isn't actually a bad one at its core. How it's executed is often frustrating (fuck you, Amai), and lacks critical instruction. Info-chan can be a little helpful in pointing you in the 'correct' direction, but ultimately what is frustrating about these 'right ways' is that they are all meant to be equally difficult, and so don't end up rewarding the player for critical thinking at all.
In all fair play, after YanDev made the change from JavaScript to C# awhile back, and the game DID run a bit cleaner after that. If you have watched any piece of media covering Yandere Sim, you likely have heard that his code is spaghetti. This is true. A hallmark of his style is multiple long chains of 'else-if' statements set in update loops for every NPC in the game.
Further, one of the drawbacks of using a fuckton of high-poly, store-bought assets and implementing no LOD means that, regardless of where these models are, they are rendered at full detail. If this were one, two, or even ten, there might not be too big of an issue. But, the game renders a large number of these NPCs to populate the school.