A new girl will fall in love with your Senpai every week - you must eliminate her before she confesses her love to him on Friday! You can kidnap her and keep her trapped in your basement, set her up with another boy, ruin her reputation, get her expelled from school, frame her for a crime, sabotage her interactions with Senpai until he hates her, or set her up with another boy. Alternatively, you can simply kill her when nobody is watching if you prefer a more direct approach!
Your actions will affect your reputation at school, since everyone knows your name and face. Maintaining the image of an innocent student requires that you behave carefully around others. You can also gain various advantages by attending classes, joining clubs, and making friends. Class attendance will help you develop new skills, joining clubs will provide you with items specific to those clubs, and making friends will enable you to get favors from them!
If you commit murder, you'll have to clean up after yourself. Using a mop and a bucket of water, wipe away all the bloodstains left behind, discard any murder weapons with your fingerprints on them, and burn corpses to cover up all evidence! You should be on the lookout for students who will take incriminating photos of you and report you to the police if they see you commit a murder...and students who will chase you down, disarm you, and capture you if they see you commit a murder!