As of the March 3rd, 2016 Build, there are currently eight personas that are fully implemented in Yandere Simulator: Loner, Heroic, Teacher's Pet, Evil, Coward, Social Butterfly, the Delinquents' Persona, and Strict. YandereDev has confirmed that there will be more personalities. However, more personas would require more animations and having a larger number of students.
The Clingy/Damsel and Sleuth personas are planned, but are not in the game yet.
Loners, Teacher's Pets, Social Butterflies, and Heroes will act hostile towards Yandere-chan after realizing she is connected to murder. They will spread rumors about her true nature and will damage her reputation by 10 points each day until they are killed. The Delinquents will also be hostile towards her upon realizing she is connected to murder, but instead of spreading rumors, they will continuously chase her until they put her into a coma. The Evil and Coward personas will have less hostile actions and will not harm Yandere-chan's reputation.
Students with different personas will react differently when the player attempts to take a picture of them. If Yandere-chan is in the Photography Club, they will not react.
- Main Article: Clingy/Damsel
This persona has not been implemented yet. Nearly all rivals will have this persona; however, Muja Kina, Osoro Shidesu, Oka Ruto, and Mida Rana may be an exception to this rule. If a rival with this persona sees Yandere-chan commit murder, they will run to Senpai and tell him Yandere-chan was responsible, which will cause an instant Game Over.
If a rival is eliminated peacefully, she will not have this persona anymore. 
- Main Article: Coward
This persona was implemented as of the February 1st, 2016 Build. Cowardly students will become terrified of Yandere-chan and will start begging her to spare their life in exchange for their silence. Cowards will cover their face if Yandere-chan attempts to take a picture of them.
- Main Article: Delinquents' Persona
All delinquents have this persona. If they see Yandere-chan carrying a suspicious weapon or a bloody weapon, they will prepare their own weapons in response. If Yandere-chan approaches a delinquent and tries to attack one, they will retaliate violently with a blow to the head, causing Yandere-chan to be rendered comatose.
If they spot Yandere-chan carrying a dismembered body part or interacting with a corpse, they will chase after her, catch up to her, and hit her over the head, causing a game over.
- Main Article: Devoted
- Main Article: Evil
Evil students will approve of the player's kill, promise not to say a word about it to anyone, and feign ignorance to the police. They will be happy to see Yandere-chan's enemies die, and wish to watch her kill again. Evil students become annoyed and will cover their face if she attempts to take a picture of them.
Friendly But Strict
Currently, the only person to have this persona is Kyoshi Taiso. The Friendly But Strict adult will act the same as a teacher and can restrain Yandere-chan. However, Teacher's Pets will not go to them to report a corpse or murder. A Friendly But Strict adult will tilt their head and smile if Yandere-chan tries to take a picture of them.
- Main Article: Heroic
If a Heroic character spots Yandere-chan murdering a student, they chase after her and will trigger a struggle mini-game when they catch her. The player must complete the mini-game successfully to defeat them. Each NPC has different levels of self-defense, which determines the difficulty of the mini-game. Heroes will give Yandere-chan a suspicious look if she tries to take a picture of them.
- Main Article: Loner
Loners will run out of school grounds to call the police if they witness murder. They will sit apart from other students, making it easier to kill them. Loners also cover their face if Yandere-chan attempts to take a picture of them.
- Main Article: Sleuth
This persona has not been implemented yet. Every student in the Photography Club will have this persona. If School Atmosphere is low, they will continuously search for the criminal to snap a picture of them. If they take an incriminating picture of the player, they will send it to the police, and this will result in an instant game over.
- Main Article: Social Butterfly
When witnessing a murder, Social Butterflies will run to the nearest crowd and then call the police. It is harder to murder around students with this persona because of the number of students that gather and can witness the Yandere-chan's actions. If a Social Butterfly sees Yandere-chan after witnessing murder, they will scream and attract attention to them, then will crouch on the ground holding their head. They will happily pose if she takes a picture of them.
- Main Article: Strict
Almost all teachers have this persona. Strict NPCs will be reported of murder by Teacher's Pets. If a teacher sees a corpse, they will call the police and then guard the corpse until the police arrive. Teachers give the player a suspicious look if she tries to take a picture of them. If she murders a student in front of a teacher, they will chase and restrain Yandere-chan.
- Main Article: Teacher's Pet
Teacher's Pets will run to their favorite teacher and tell them about Yandere-chan's kill. Teacher's Pets will give her a suspicious look if she tries to take a picture of them.
- If a student with the Teacher’s Pet personality discovers a corpse or witnesses murder, they will run and tell a teacher.
- If a teacher is informed of a murder, they will run to the scene of the crime and investigate it.
- If a Teacher’s Pet witnesses a murder/corpse, but someone else is already reporting a murder/corpse, then the student will run and hide in a classroom instead of informing a teacher.
- If a Teacher’s Pet informs a teacher of a murder/corpse and leads the teacher to the scene of the crime after the player has already cleaned up the evidence, the teacher will conclude that the student was pulling a prank on her, leaving the student mentally scarred.
- If a Teacher's Pet reports a murder and then Yandere-chan moves the body far away from crime scene, even if no other evidence has been cleaned up, the teacher will conclude that the student was pulling a prank on her and will not call the police. However, the teacher will discover the evidence at the end of the day, as normal.
- Hero Complex (Became Heroic)
- Sadistic (Became Evil)
- Social Butterfly (Re-implemented in February 1st, 2016)
- YandereDev has considered adding a vigilante/perfect student persona, but has not fully decided yet.
- It is also unknown if this has become the Sleuth persona.
In the future, if students have witnessed homicide or corpses enough, they will become "Broken". If they see any more murderous activity, they will not react to corpses or murder anymore.
This persona will take a picture of Yandere-chan committing murder and upload it to social media, causing an instant game over. 
- It may be possible that if tortured, students' sanity will go down in different amounts depending on persona. Strength will not be a factor.
- If a student witnesses murder, they will hide their face when Yandere-chan aims a camera at them, regardless of their persona.
- Students will act on their persona if they discover their crush's corpse. If they have an interaction event with their crush, but their crush is dead, then they will go to the event spot and mourn. Some emotional NPCs might weep.
- YandereDev planned to include about five personas in the final game. Now the expected number of personas has been exceeded.
- YandereDev would like all personas to have different idle animations when paranoid.
- YandereDev doesn't think that gender specific personas are a good idea.