On the schemes menu, the description is, "This scheme will end with your rival poisoned to death".
Location of Poison
The poison is located on the second floor in the western wing, in the Science Lab. The only way Yandere-chan can successfully obtain poison is by having twenty study points invested in the Chemistry stat.
If she doesn't have Chemistry Rank 2, then she cannot take the poison from the shelf, even if the player knows its location. If the player is having trouble finding the poison, they can use Yandere Vision to pinpoint its location. The poison is circled in cyan.
Alternatively, poison can be obtained through the drops menu.
How to Poison
In the debug builds, Yandere-chan is able to poison the test rival, Kokona Haruka.
During Wednesday at lunchtime, Kokona will walk down to the plaza. Before entering, she will see Senpai sitting on the fountain. Kokona will place her lunch on a bench, hide behind a tree, and plan her confession to Senpai on Friday. While she is watching Senpai, Yandere-chan can pour the poison into her lunch. Kokona will soon walk to her bench and sit down to eat. If the lunch is laced with poison, Kokona will begin to cough loudly. She will then fall to the floor, clutching her throat, quickly dying from the poison.
Before the November 15th, 2015 Build, she sat at the middle southern bench on the rooftop. Kokona watched Senpai from the middle ventilation shaft.
If Kokona is not poisoned, she will eat until all of her food is gone and will walk back to class.
In future builds, other students will notice Yandere-chan putting poison into other students' food.
If a student sees the poisoned victim, regardless of their persona, they will run to a teacher, possibly Nasu Kankoshi in future versions. The teacher will contact the paramedics as well as the police, and the school day will end immediately.
When the paramedics and police arrive, they will be unable to revive the student. They will treat the death as a murder case. They will then try to search for any corpses or weapons on the ground. If no other corpses or weapons are found, they will leave since they don't have enough evidence to perform an arrest. If weapons and corpses are found, the game will treat the other deaths as homicide cases and will begin to look for evidence for the deaths, along with the poisoned corpse. If Yandere-chan hides a poisoned student's body but does not dispose of it by the end of the day, a teacher will still find the corpse and call the paramedics. The School Atmosphere will then decrease by ten points.
YandereDev has stated that in the final version of the game, other students will notice the person loudly choking to death instead of just ignoring them.
Emetic poison was implemented into the game in the January 3rd, 2017 Build. Emetic poison makes the victim sick, rather than killing them. When a student ingests emetic poison, they will run to a bathroom to throw up.
In the future, emetic poison will allow Yandere-chan to sabotage rival events, or to put a rival in a more vulnerable position, such as hunched over a toilet.
- Poisoning was implemented in the June 1st, 2015 Build.
- In the future, the player may be able to poison a rival's water. The method would be challenging and would require a lot of stalking.
- YandereDev has mentioned that in future builds, Yandere-chan can poison a student (possibly non-lethally) to distract a nurse. This will cause her to take out her medicine cabinet key, which will be necessary to access the drugs inside. The player can then steal the key once the location is discovered to steal tranquilizers for kidnapping. It is unknown if this is still the case.
- When Kokona Haruka gets distracted by Senpai, the player can turn on Titan Mode and Kokona Haruka's lunch will grow with her when she holds it.
- The poison used is barium acetate, which works incredibly fast and is almost untraceable. A $150,000 poison detection machine is required to detect barium acetate in autopsies. Buraza Town does not have this machine.
- If a majority of rivals are "accidentally" poisoned, Senpai will worry that he is cursed.