A weapon will usually fall into one of four categories: small stabbing weapon, large stabbing weapon, small bludgeoning weapon, and large bludgeoning weapon. There's also the circular saw, which is normally used for dismemberment, but it can also be used for murder.
Currently, there are 20+ weapons Ayano Aishi can use to murder someone. Each weapon has its own strengths and weaknesses, so the player has a lot of options when it comes to killing.
Some weapons are considered non-suspicious and will not result in a reputation penalty if Ayano is seen carrying them, like the scissors, screwdriver, or box cutter. Some weapons will be seen as suspicious unless Ayano is a member of a certain club, like the baseball bat in the Sports Club or the shovel in the Gardening Club. Some weapons are suspicious no matter what, like the fire extinguisher or the pipe wrench.
Some weapons can be easily concealed, while others cannot. Ayano cannot use a non-concealable weapon when fighting against NPCs, because the weapon is too unwieldy to use in close quarters and will result in automatically losing the struggle. Any non-concealable weapon can be hidden and carried inside a cello case, a trash can, or a weapon bag.
If Ayano drops a weapon 10 meters away from its initial location, it will be considered as suspicious and will catch someone's attention. Students that find a dangerous weapon on the ground will report it to their teacher. The teacher will then pick it up and place it inside a box in the Faculty Room. If the weapon is bloody, the teacher will call the police, and any other students that see the bloody weapon will run to their classrooms. If the weapon is not considered dangerous, students will pick it up and return it to its original position, leaving their fingerprints in the process which allows the player to frame them for murder.
The majority of non-concealable weapons will get bloody if the player attacks the victim from the front, though no blood will get on the player. The Katana, Fantasy Sword, Sword, Scrap Metal, and Circular Saw are all non-concealable and will get the player bloody no matter which type of attack is executed. On the other hand, the Dumbbell, Pipe Wrench, and Fire Extinguishers will never get the player or weapon bloody no matter what type of attack is executed.
As of the Big June Update of 2022, there are seven weapons that won't return once disposed of because they are one-of-a-kind. They are the Katana, Magical Girl Wand, Fantasy Sword, Sword, Ritual Knife, Old Axe, and the Guitar.
The game will track whose blood and whose fingerprints are on each weapon. If Ayano does not dispose of a bloody weapon, a teacher will find it and call the police, who will then come to perform an investigation. The police will try to trace the weapon back to Ayano. If she wears gloves, the police will not find her fingerprints on the weapon. As a result of this, she is able to frame other students by using weapons they have touched to commit murder.
The easiest way to frame a student involves a box cutter, a roll of packing tape, and an empty box. Ayano pretends that she got the box cutter stuck while opening the box. As a result, any student she talks to, besides the Delinquents and the Student Council, will agree to help her, getting their fingerprints on the weapon.
In earlier builds, Ayano would automatically drop all weapons when the day ended at 6 PM. This would have been troublesome for a player who forgot to dispose of a weapon. A teacher would then find it and call the police, and the police could immediately trace the weapon to Ayano, causing a Game Over. Currently, she will instead take the weapon home and dispose of it. If the police arrive at school, however, they will search the students and find the bloody weapon on Ayano's body, so she will still be arrested.
- Main Article: Reputation
If students see Ayano carrying a dangerous weapon, they will see her as suspicious, thus damaging her reputation by ten points during high School Atmosphere, fifteen points during medium School Atmosphere, and twenty points during low School Atmosphere. Apologizing to a student will give her back some of the reputation she lost. If a friend or a student that is being seduced by Ayano sees her with a weapon, her reputation will be affected by eight points. If she is in the Occult Club, it will take longer for students to notice her carrying a dangerous weapon.
If Senpai sees Ayano with a dangerous weapon, he will become terrified of her, resulting in the "Heartbroken" Game Over. If a teacher or a student council member sees Ayano with a dangerous weapon, she will be sent to the Counselor's Office. If a teacher sees her holding a dangerous weapon after a student has been murdered, she will assume Ayano killed the student and attempt to pin her down, apprehending her.
The scissors, box cutter, and screwdriver are all classified as non-suspicious weapons. Ayano will not be considered "visibly armed" when carrying these weapons. In the final game, the only weapons available will be ones found in a school environment, unless she brings a weapon from home from the Hardware Store in Buraza Town, or asks Info-chan to leave a weapon at the back of the school.
If Ayano holds a suspicious weapon near the delinquents, they will assume a menacing stance, ready to fight. They will lower their guard after she puts it away, and taunt her. If the player walks up to the delinquents multiple times, a battle minigame will activate. Winning this minigame will result in being able to take the delinquent's weapon and frame them for murder if the player was wearing gloves.The police can then trace the fingerprints on the weapon to the delinquents as long as Ayano did not leave her fingerprints on the weapon as well.
If multiple people have touched the murder weapon, the last person to touch the weapon would be framed, or Ayano would be arrested if she left her fingerprints on the weapon at any time. If many people are framed for many individual murders at once, the person "responsible" for the latest murder committed would be arrested only. This is due to programming limitations.
- Main Article: Sanity
- Stealth kill: Performed from behind, with the victim unaware. Quick, quiet and clean.
Low sanity kill animations last longer than high sanity ones.
- High sanity kill: Efficient, but not as fast as a stealth kill. Produces some extra noise and blood. Takes two seconds.
- Medium sanity kill: The victim struggles a little bit. The kill is sloppy and messy, taking more time. Takes four seconds.
- Low sanity kill: Very prolonged killing animation that is brutal and sadistic. Victim screams and struggles to get away. The player has the option to make Ayano continue to attack her victim indefinitely by mashing the "attack" button, causing a segment of the animation to loop until the player stops mashing the button. Takes six seconds if not prolonged by button mashing.
More animations could show additional kill techniques that vary depending on weapon type and current sanity level. Ideally, every weapon will eventually have an unique animation set. If this cannot happen, a less ideal scenario would be that each weapon type, (short, stabbing, long, and bludgeoning), has its own animation set. At worst, all weapons will have the same animation.
- Main Article: Axe
- Main Article: Baseball Bat
Found inside one of the storage rooms in the gym and can be dropped by Umeji Kizuguchi, Seishiro Sadanaga, and/or Tiru Sutoriku. Seen as suspicious unless Ayano is a member of the Sports Club. Cannot be concealed without a weapon bag or other object. Ayano cannot use it to fight an attacker. She can pass it through a metal detector, since it is made out of wood. You can combine the bat with nails in the Workshop to create a spiked bat.
- Main Article: Boken
Can be dropped by Hokuto Furukizu, Taichi Hiranaka, and/or Doremi Shimahara. Seen as suspicious and cannot be concealed. Ayano cannot use it to fight an attacker. Can be passed through a metal detector, since it is made out of wood.
- Main Article: Box Cutter
Found in the Art Club. Seen as non-suspicious and can be concealed. Can be used to frame students by putting it in a closed box, then asking students (other than Student Council members and Delinquents) for help getting it out. Cannot be passed through a metal detector. Ayano can fight back with it.
- Main Article: Circular Saw
Found inside the Gardening Club's shed. Can also be used to dismember a corpse. Seen as suspicious and cannot be concealed. Ayano cannot use it to fight off an attacker. Cannot be passed through a metal detector.
- Main Article: Crowbar
Can be dropped by Gaku Hikitsuri, Shichiro Kurosapu, and/or Murasaki Nobumoto. Can also be used to open a manhole cover, allowing the player to dump bodies into the sewer. Seen as suspicious and cannot be concealed. Ayano cannot use it to fight an attacker. Cannot be passed through the metal detector. Ayano cannot fight back with it.
- Main Article: Dumbbell
Five of them can be found inside one of the storage rooms in the gym. Can be used to crush students or attack them. Seen as suspicious, unless Ayano is in the Sports Club. Cannot be concealed. Cannot be passed through a metal detector. Ayano can't fight back with it.
- Main Article: Fantasy Sword
Found inside the Drama Club. Seen as suspicious unless Ayano is in the Drama Club. This weapon cannot be concealed. Ayano cannot use it to fight an attacker.
- Main Article: Fire Extinguishers
They are found on all floors near the bathrooms in the west wing. Ayano can wield it and hit students. Seen as suspicious and cannot be concealed. Ayano cannot fight an attacker with it.
- Main Article: Guitar
Found inside the Light Music Club. Seen as suspicious unless Ayano is a member of the club. Ayano cannot use it to fight off an attacker.
- Main Article: Katana
Found inside a locked display case in the headmaster's office. Seen as suspicious and cannot be concealed. Ayano cannot use it to fight an attacker.
- Main Article: Knife
Found inside the Cooking Club. Seen as suspicious. It is concealable and cannot be passed through metal detectors. Ayano can fight back with it.
Magical Girl Wand
- Main Article: Magical Girl Wand
Found inside the Drama Club. Seen as suspicious unless Ayano is in the Drama Club. This weapon cannot be concealed. Ayano cannot use it to fight an attacker. Ayano can use this weapon to activate the Magical Girl Pretty Miyuki easter egg after completing the demo. Made of plastic, so it can be passed through a metal detector.
- Main Article: Makeshift Knife
Can be crafted at the workshop. Seen as suspicious and can be concealed. Ayano can use it to fight an attacker. Made from glass, wooden sticks and bandages, so it can be passed through a metal detector.
Found in the Faculty Room. Can also be used to lift the cover of the manhole in the Outdoor Cafeteria. Seen as suspicious and cannot be concealed. Ayano cannot use it to fight an attacker. Cannot be passed through a metal detector.
- Main Article: Old Axe
Found behind the Gardening Club's shed. Seen as suspicious and cannot be concealed. Ayano cannot use it to fight an attacker. Cannot be passed through a metal detector.
- Main Article: Pipe
Can be dropped by Hayanari Tsumeato, Togo Atatsuma, and/or Akari Komiyaku. Seen as suspicious and cannot be concealed. Ayano cannot use it to fight an attacker. Cannot be passed through a metal detector.
- Main Article: Pipe Wrench
Found near the swimming pool, It can also be used to sabotage the pipes of a drinking fountain or sink to help electrocute or soak a student. Seen as suspicious and cannot be concealed. Ayano can't fight back with it.
- Main Article: Ritual Knife
Found inside the Occult Club. Can also be used to start a Demonic Ritual. Seen as suspicious but can be concealed. Killing someone will cause this weapon to spawn a brief cloud of black mist. Ayano can fight off attackers with it.
- Main Article: Scissors
Found in the sewing room. Seen as non-suspicious and can easily be concealed. Cannot pass through a metal detector. Can be used to fend off attackers.
- Main Article: Scrap Metal
Found near the Incinerator. Seen as suspicious and cannot be concealed. Cannot be used to fight attackers. Cannot be passed through a metal detector.
- Main Article: Screwdriver
Found in the workshop. Can also be used to expose the wiring of a power strip so that a student can be electrocuted, or to sabotage various things like metal detectors and vending machines. Seen as non-suspicious and can easily be concealed. Cannot pass through a metal detector. Can be used to fight attackers.
- Main Article: Shinai
Can be dropped by Dairoku Surikizu, Saburo Meshino, and/or Raimu Ichijo. Seen as suspicious and cannot be concealed. Ayano cannot use it to fight an attacker. Can pass through a metal detector, since it is made of wood.
- Main Article: Shovel
Found outside the Gardening Club's shed. Seen as suspicious unless Ayano is in the Gardening Club. Cannot be concealed. Can also be used to dig and fill up holes in the Gardening Club's vegetable garden to bury up to nine corpses. Ayano cannot use it to fight an attacker. Cannot be passed through a metal detector.
- Main Article: Sword
Found inside the Drama Club. Seen as suspicious unless Ayano is in the Drama Club. This weapon cannot be concealed. Ayano cannot use it to fight an attacker. Cannot be passed through a metal detector.
- Main Article: Syringe
Found in the Infirmary. Can also be used with a tranquilizer in one of the gym's storage rooms for kidnapping students and rivals. Seen as suspicious but can be concealed. Can be used to fight an attacker. Can be passed through a metal detector.
Possibly Planned Weapons
Weapons that might be added in future builds:
- Butcher Knife.
- Gardening Sickle.
- Painting Knife.
- Soda Cans.
- Gardening Shears.
- Glass Cutter.
- Fire Poker.
- Nambu type 14
- Bamboo Tanto Knife
There will be different types of weapons in the future, like two-handed, swinging, stabbing, and strangling weapons.
|“||What do you want?! Don't hurt me! Stay away!||”|
— A student seeing a fully insane Ayano bloody and carrying a weapon.
— Delinquents after seeing Ayano hold a weapon.
|“||Don't even think about it!/I'll crack your skull open!/Looking for a fight, huh?!/You gotta death wish?!/Try it, I dare you!||”|
— Delinquents while watching Ayano hold a weapon.
|“||What are you doing, carrying something like that around? Have fun explaining this to the guidance counselor!||”|
— A teacher after catching Ayano holding a weapon.
|“||Just what do you think you're doing?!||”|
— A teacher resisting Ayano's attack with a weapon before pinning her to the ground.
|“||Why do you have a weapon? What are you going to do with that thing?! Stay back!||”|
— Senpai after seeing Ayano visibly armed.
|“||Yeah, that's what I thought. Coward./All talk and no action, huh./Hahahaha... I knew you didn't have the guts.||”|
— Delinquents after seeing Ayano put away a weapon.
- Non-concealed weapons (excluding the katana, the circular saw, the baseball bat, and the swords from Drama Club) will count as a "bloody weapon" if the player attacks students on the front, even if the non-concealed weapons don't get bloody if the player attack students on the front.
- If the player washes a weapon after getting it bloody from killing someone, it will still count as a "bloody weapon" in the police investigation.
- As of the October 15th, 2017 Build, sound effects for picking up weapons have been added.
- It is theoretically possible for a pencil to become a weapon, but YandereDev does not find it cool enough. He wants all weapons to be cool.
- There are more weapons available in the small town, but they are currently unprogrammed.
- YandereDev has stated in an interview that the katana might be something that Kocho Shuyona confiscated and just never got rid of.
- As of the November 15th, 2016 Build, the katana is located in the Headmaster's office.
- The headmaster was said to have never touched the katana since 1988.
- Ranged weapons will most likely not be in the game. This is likely to prevent the game from becoming too easy, as nobody has defense against any ranged weapon (like a helmet). For example, with a sniper rifle/crossbow or even a pistol (which is easily concealable), all what one needs to do is to shoot, hide, then dispose of the weapon. It can be said that even without a silenced weapon, it is extremely easy to win Senpai by killing all the rivals. The game is also a school environment, so most likely very few opponents will ever get to use a ranged weapon that definitely requires another to defeat.
- However, while the player cannot use any, there are NPCs with ranged weapons. The most obvious example is perhaps the headmaster who owns a Taser that causes great damage to anything living it zaps (he currently only attacks the player with it) and has a short range (longer than every other weapon).
- The police are a good candidate, though they are never seen with any ranged weapons, as most police officers will carry a pistol at the very least for security purposes.
- Formerly, there were only three regular animations with a murder weapon: a sideways stab to the neck for the knife, scissors, box cutter, screwdriver, syringe, and ritual knife, a slam to the head for the katana, baseball bat, shovel, dumbbell, and a unique animation for the circular saw. There is also a stab in the head whenever Ayano wins a fight against a Heroic student and another when brainwashed, kidnapped victims finish a murder-suicide. All of the weapon animations have been replaced with the sanity-based attacks, except during fights against a Heroic student.
- The animation used for the larger weapon, high sanity attack animations, (except the circular saw) is also used for when the old delinquents attack Ayano.
- Ayano intends to kill when the player presses the "attack" button. There is no chance of knocking the victim unconscious or leaving them "Half-dead".
- There is a possibility that a sniper mini-game will be added purely for fun. However, a sniper equivalent in the game is unlikely. With one, it will harm the gameplay experience since the weapon will likely sustain against several rivals before it risks discovery by Senpai.
- It is very important to YandereDev that there's a cheat code or Easter Egg which unlocks a giant sci-fi energy scythe.
- In the future, it is possible that if students see a certain weapon lying around, they will give it to a teacher.
- YandereDev does not have the animations nor the models for choking someone with a rope or a chain yet. 
- Cleaning bloody weapons can be done using a sink and the Drinking Fountains.
- YandereDev does not want to add ranged weapons to the game due to the sharp increase in school shootings in the United States in the past decade.
- YandereDev's favorite weapon is the cyborg ninja sword.