Debate Mode is where the deduction game stops being a visual novel. You are given a room full of people with reasons to lie, a limited amount of credibility, and a set of clues that are only worth as much as the argument you build around them.
You present evidence and the room reacts. The critical rule: presenting the wrong evidence costs HP. Your HP is not a health bar for the character — it is the room's patience with you. When HP reaches zero, the run does not restart; it goes to a failure ending. That makes every accusation a real wager.
A clue is not a puzzle piece to be collected and handed over. A clue is a bullet with a cost. Because the disorder effects obscure the scene, you will be tempted to accuse on inference alone — and inference alone is exactly what the HP system punishes. The game is asking you to hold a partial picture together longer than is comfortable before you commit.
Both confirmed chapters run four debate rounds. Chapter 1 ends in 認知干擾 (cognitive interference); Chapter 2 ends in memory rewriting. And Chapter 2 is explicit that three failures lead to the 集體誤判 bad ending — so the game is keeping a running count across the chapter, and it will tell you.
Chapter 2 closes with the choice to publish what you found or keep it private to your sister. It is the only explicitly stated choice in the game so far, and given that Lain's power lets him make others see his hallucinations, publishing and telling the truth are not obviously the same act. That is the kind of question this game is built to make you argue about.