The daily loop
Each day you teach a class, then choose: stay overtime or go home. Staying means grading papers until the clock hits midnight, when the room shifts and the encounter happens — then you wake at your desk, confused. Going home leads somewhere else entirely, with a separate mystery and a different woman. Some days force the choice, so you cannot camp one path.
Grading is the real detective work
The grading minigame is not filler — it is how the mystery is delivered. You read student answers and assign grades, and one student's paper changes over time. Day one is normal handwriting. By day three there is a small heart in the margin. Day five reads "sensei you smell nice." Day seven: "see you tonight sensei." You are literally grading her confessions without realising it, and that is how you work out who she is.
The cracks in the story
On day three she says "later again sensei?" in class and you freeze, then convince yourself you misheard. Day five brings a hair on your desk that is not yours. Day seven, lipstick on your shirt. Day eight, she says something a student said in class earlier that day. Day ten she is still there for half a second after you wake. Day twelve is the full reveal: it was never a dream, she has been coming every night, and you have been responding.
The cope is the mechanic
For a long stretch you believe it is all dreams and treat it as harmless — you even start looking forward to overtime. The design point is that you are complicit in your own delusion, because the alternative is worse. The horror is not the encounters. It is how long you let yourself not ask.
You will not miss content
There is no content gating. Your nightly choice determines which woman you see tonight, not whether you ever see her — the other reappears within one to three nights, and roughly one night in four is quiet so the story can advance. Replaying changes the order, her mood toward you, and the late-game ending, rather than unlocking scenes you were locked out of.