Act 3 is the penultimate act of the game, featuring only Monika and the player.
When the game is restarted, the player and Monika are alone in the classroom. Outside the window is a pulsating space-like background. At this point, the game checks to see if either of two programs used for recording or streaming game footage is open. It does this by looking for any of four executable file names are currently running:
$ stream_list = ["obs32.exe", "obs64.exe", "obs.exe", "xsplit.core.exe", "livehime.exe", "pandatool.exe", "yymixer.exe", "douyutool.exe", "huomaotool.exe"]
If none of these are open, the game will attempt to guess the player’s real name by accessing the name of the computer account being used. She notes that she’s fallen in love with the real user playing the game, not the façade in the game world.
Monika will proceed to talk about how she deleted Natsuki and Yuri, noting the presence of the characters folder. If the game is running on Steam or on a Mac computer, she will elaborate on how she accessed the folder in question. Later, she activates the poem game. None of the words usually present are available to be chosen. Instead, the player is given the choice of choosing between ten instances of word "Monika," usually corrupted. To construct these corruptions, each letter is iterated through. For each letter, there is a chance that it will be replaced with a space. If this doesn’t happen, then there is a chance that it will be replaced with a random character from the same pool of characters that is used to generate glitch text. Which words are chosen has no bearing on the progression of the game.
Later, the game will once again check to see if any of the recognized streaming programs are open. If so, she will jokingly reprimand the player for recording her without warning, then pretend to lead up to a jumpscare. Shortly after claiming she was "just kidding" about the jumpscare, she will abruptly perform a jumpscare.
If the player quits and reopens the game during this portion of the game, Monika tells the player that she had a bad dream and asks the player to investigate the cause. If the player continues to quit and reopen the game, Monika will realize that this is what causes the dreams, initially asking the player to not do it, but later stating that she doesn’t mind it because it means that the player returns to her. There are five such interactions with Monika. Restarting the game after this causes her to simply repeat the fifth interaction.
While going through Monika's topics, the skip button is enabled. When pressed, Monika instantly reacts to it, chiding the player for trying to skip her dialogue, then disabling it for the rest of the act and continuing with her previous topic.
The game stays in this state of Monika looping through various topics until her
.chr file is deleted in the characters folder. Once the file is deleted, she will express feelings of betrayal, but will also show remorse. She will then delete her own character file if it's been restored, then restart the game to the title screen from where Act 4 will begin.