In the game, the knife is found on the rooftop and inside the Cooking Club. The knife is seen as suspicious, but can be concealed. If a student sees Yandere-chan holding a knife, her reputation will drop by ten points at high School Atmosphere.
The knife can be used to frame the rivals. Every day after school, Kokona Haruka, the current test rival, will use a knife in the Cooking Club. If Yandere-chan wears gloves and kills another student with the knife, it will be traced to Kokona and she will be arrested.
If Yandere-chan joins the Cooking Club, she will have easy access to knives and will not be considered suspicious when holding a knife in the room.
There are 4 killing animations for the knife, depending on Yandere-chan's level of sanity.
- High Sanity: A sharp stab to the right side of the head.
- Medium Sanity: The victim tries to defend themselves, then gets stabbed in the right shoulder by Yandere-chan; then they are stabbed in the right side of the head.
- Low Sanity: She will grab the victim's neck and tackle them to the ground, the victim will try to defend themselves, as they are stabbed in the head multiple times.
- Stealth Kill: She will cover the victim's mouth, then stab them in the head.
|“||Is that a knife? You shouldn't bring something like that to school.||”|
— A student seeing Yandere-chan holding a knife.
- The knife was implemented in the February 1st, 2015 Build, making it the oldest weapon in Yandere Simulator.