Homicide

Homicide is a quick but messy way to eliminate someone in Yandere Simulator.

Method
In order to murder, the protagonist needs a weapon. With a weapon equipped, she can attack a nearby NPC. The protagonist's uniform will have several splatters of blood on it, and her sanity will decrease. The more people she murders, the more blood there will be on her and the more sanity she will lose. Once the protagonist has killed four people without stopping to restore sanity, her sanity will be at its lowest. Additional kills will not decrease it further.

The player is able to wear gloves in order to prevent a weapon from being traced back to her. When a student is killed, blood will splatter on the gloves as well.

The protagonist will only be able to kill a teacher with a weapon if she has enough study points in Physical Education, but this has not been implemented yet. Trying to attack a teacher without enough study points will result in expulsion. Currently, the only way to kill them without mods is with Easter Eggs, such as Cirno Mode or Falcon Mode.

Consequences
NPCs who have been murdered will not return to school the next day unless the player restarts the week or day, except for teachers, who currently respawn. In the future, they will be replaced by substitutes. When the protagonist kills unnecessary students, she may lose events (e.g. killing Saki before she can have her rooftop conversation with Kokona).

Almost everything involving murder will lower the School Atmosphere, even if most evidence of it is cleaned up.

As of the September 1st, 2015 Update, people will scream loudly right before they are murdered. Other NPCs can hear the scream if they are within its range, which increases as School Atmosphere drops. Those in the scream's range will turn around and then scream as well. The only way to murder students in the lowest School Atmosphere without being heard is to do it in a secluded area, like a bathroom, far away from other NPCs so nothing can be seen or heard.

If the player kills a club leader or kills enough of a club that there are less than five members left, then the club will disband forever. This will cause some students' routines and appearances to change. (The Occult Club, instead of going inside their club room, will converse outside it; Martial Arts Club members will no longer wear their headbands; etc.)

In future updates, as sanity drops, killing animations will take longer, and after a student witnesses two murders, they will flee immediately. At low School Atmosphere, they might even walk with their phones out, trying to get a picture of the killer. Or, they might take a picture immediately after witnessing murder, whicih would lead to an instant Game Over.

In the future, when a student is murdered, a memorial will be held for them the next day. The player will lose the morning of that day.

Witnesses
When a student witnesses the protagonist murder another student, the witness may react in several different ways depending on their persona. So far, only four personas have been fully implemented into the game: Loner, Teacher's Pet, Heroic and Strict. YandereDev was thinking that if multiple students witnessed murder, they will all simultaneously attempt to restrain the player, but it is not in the game for the moment.

If a witness with the Loner, Teacher's Pet, or Heroic persona is left alive, they will damage the protagonist's reputation by ten points each day. When the player tries to interact with the student for the first time since the murder, they say that they will tell everyone about the protagonist's true nature. Afterwards, they will tell the protagonist off every time she tries to speak with them.

In the future, students will not report the protagonist for murder if they hated the victim. It's unknown if this applies to all students.

Club Members
Club member personas are varied. If the player murders a student in front of a club member, they will initially act upon their persona. Afterwards, the club member will tell the club leader what the protagonist did, and she will be kicked out of the club forever. She will also be kicked out if the club leader sees her commit murder. If any members see the protagonist commit murder, but she isn't a member of the club, she will be barred from joining it.

Loner
If a student with the Loner persona witnesses murder or sees a corpse, they will flee the school and call the police, giving the player a total of five minutes to dispose of the corpse, blood, and any other evidence. If the player manages to do so, the police will not be able to uncover any evidence that a murder took place on school grounds, and the protagonist will not be arrested.

Afterwards, the student will refuse to talk to the protagonist and will damage her reputation every day they are left alive.

Teacher's Pet
If a student with the Teacher's Pet persona witnesses a murder or sees a corpse, they will run to their favorite teacher and inform them of what they have seen. The teacher will request that the student lead her to the corpse. If the protagonist has cleaned up the crime scene before the teacher arrives, the teacher will accuse the student of pranking her and will return to her classroom. This will leave the witness mentally scarred for the rest of the game. In the future, the witness will try to convince the other NPCs that the protagonist committed murder, impacting her reputation negatively. If more than one student with the Teacher's Pet persona witnesses murder, the first witness will inform a teacher and the others will hide in their classroom.

Afterwards, they will refuse to talk to the protagonist and will damage her reputation every day they are left alive.

Strict
If those with the Strict persona see a corpse or a murder they will guard the body and call the cops.

If a teacher witnesses the protagonist murdering a student, or has realized that she is the murderer, the teacher will chase her and pin her to the floor once she is caught. It is not currently possible to outrun a teacher.

Heroic
If a student with the Heroic persona witnesses a murder that is not a murder-suicide, they will try to apprehend the protagonist by chasing after her. If they catch up and grab her while she has a weapon, this will cause them to enter a "Struggle" minigame, where the player has to press several buttons rapidly in order to fight back and kill them. If she fails to get out of their grasp, they will pin her to the ground and a Game Over will appear. If the protagonist has no weapon, then she will be pinned down immediately once the student catches her. If the player is in the Martial Arts Club, then she will instantly win these fights.

If a Heroic student sees evidence of murder, but not the murderer themselves, they will act upon a Teacher's Pet persona.

Evil
This persona has not been implemented yet. If a student with the Evil persona witnesses a murder, they approve of the kill and will feign ignorance to the cops.

Fragile/Coward
This persona has not been implemented yet.

If a student with this persona witnesses a murder, they will beg the protagonist to not kill them and won't report the murder. It's unknown if this persona will be named "Coward" or "Fragile".

Clingy/Damsel
This persona has not been implemented yet.

If a rival witnesses a murder, they will run to Senpai and tell him all about it. The player will get an instant game over.

Cleaning Up After Murder
In order not to be arrested by the police, or to avoid lowering School Atmosphere, the player must dispose of the evidence of a murder. The player can use Yandere Vision to find any evidence of murders, including corpses and blood.

Avoiding Being Arrested
To avoid being caught, the player only has to dispose of the evidence pointing to them as the murderer. The protagonist must dispose of the bloody weapon and uniform in the incinerator, and wash the blood off in the Shower Room and change into a clean uniform. If gloves were worn while committing murder, both the gloves and uniform must be disposed of, but the murder weapon can be left behind without the player being caught, as it cannot be traced back to the protagonist.

Avoiding Low School Atmosphere
To avoid lowering School Atmosphere, the protagonist must clean up all evidence of a murder. The corpse must be dragged and dumped in the incinerator, which is currently located to the left of the school gate.

All blood pools must be mopped up. Dragging a body creates more pools of blood as it bleeds out, and stepping into pools of blood will leave bloody footprints. If the area where the corpse was left is mopped up before dragging it, significantly less or no blood will follow when dragging it. Buckets, sinks and mops are currently located all around campus are are used to clean up the blood.

The protagonist must go to the Shower Room, take off her bloody uniform at her locker and wash off the blood at one of the stations. Then, she can possibly change into another outfit.

Corpses, murder weapons, bloody uniforms and gloves, if used, can all be disposed of in the incinerator and burned. It will take one in-game hour for all evidence to be destroyed once the incinerator is activated.

Framing
The protagonist has the choice to clean up their murder by framing another student for the crime. By doing this, School Atmosphere is fully restored, as everyone believes the killer to have been caught. This has been implemented but you can only frame Kokona Haruka by using her knife in the cooking club, for now.

Failure to Clean Up
If the player fails to clean up the mess from a murder, one of two things will happen.

No Witnesses
If there are no witnesses, or none that are left alive, a teacher will come across the corpse(s) when the school day has ended while walking through the school to tell any lingering students to leave. If there's no incriminating evidence on school grounds, the protagonist will not be arrested. However, if there is any evidence with it, the police will arrest the protagonist. The School Atmosphere will drop by ten points per corpse discovered.

If pools of blood, bloody gloves, bloody weapon(s), or a bloody uniform are left out in the open after the school day ends, a teacher will find them and call the police. If the protagonist does not correct her sanity before school ends, then a teacher will see her, but not do anything. When the police arrive, they will search for any of these variables. If the protagonist is hiding a bloody weapon on her, they will arrest her as well.

Police
The police will be able to tell that the protagonist was the murderer by scanning her DNA and seeing if it matches the bloodstained weapon, clothes, or gloves. They will also take her into custody if she displays erratic behavior. The protagonist may eventually confess to her crimes in certain Game Overs.

Trivia

 * In the future, it should be possible for Yandere-chan to murder people with her bare hands, but only under very specific circumstances.
 * In the final game, there will be a unique special ending if the entire student body is murdered in a single day.
 * Murdered students' parents, as well as other students, will notice the disappearance of the murdered student.
 * If a mind-broken student kills someone, the other students won't notice the murder, only the corpse.
 * There's an upcoming feature where a flower will be placed on a student's desk after their corpse is found. Currently, it only appears on Kokona Haruka's desk if she dies.