|Persona|| Coward (since 2/1/2016)|
Loner (9/15/2015 – 1/15/2016)
Oka will not be present at school for the first few weeks of the game. While she is absent, Shin Higaku will be her substitute. The substitute will allow the player to join the club and participate in club activities while Oka is absent. In the debug build, the player will be able to see Oka walking around, but her current features and routine are temporary and will change in the future.
Oka's first hairstyle in the November 15th, 2015 Build was exactly the same as Sakyu Basu's, except with hair covering her left eye. It was light purple.
As of the December 2nd, 2015 Build, she has messy, shoulder-length hair that is dark blue. She has a fringe hanging down the middle of her face, flowing across her right cheek. Her eyes are light purple. She has large black rings around her eyes due to lack of sleep. Her lips and skin are pale, and the upper half of her face is slightly shadowed. Since she is a club president, she wears a "Red Armband of Leadership" on her left arm. Her bust size is 1.
Like all Occult Club members, Oka wears a black choker. However, instead of having a crescent moon on it, it has a silver spider. If the Occult Club disbands, she will not wear the choker anymore.
She walks very slowly, with her hands clasped together. Oka is always looking shyly at the ground. As of the June 1st, 2016 Build, Oka wears light blue-grey thigh high spiderweb stockings and fingerless gloves. Her panties are also black. In the future, Oka will have very pale skin. According to her full body reference, it appears that in the future, Oka will have a pentagram drawn on her armband.
In Oka's original design, she was supposed to wear a turtleneck underneath a dark blue blazer. It was scrapped because Oka's model could not support two models of clothing at the same time. As of the April 10th, 2017 Build, Oka can wear this outfit by pressing the A key in the easter egg menu.
YandereDev states that she may be the shortest rival.
"Oka is the president of the school's occult club. She is completely convinced that ghosts, demons, and black magic really exist, and wants to dedicate her life to proving that these things are real.
Oka is absent for school during the first three weeks of gameplay for mysterious reasons. As soon as she returns to school, she is immediately smitten by Senpai. Due to the fact that she falls for him in an extremely short span of time, she believes that there must be something supernatural about him, and begins studying him intently.
She is an awkward girl who is regarded as "creepy" by the majority of the school, but she is actually quite harmless, and some people even find her to be endearing. Perhaps Senpai will think that there is something charming about her unusual nature..."
Oka is a stalker, but not a yandere, as she is too shy to harm others. Her mannerisms are meant to make her look shy, timid, and socially awkward. She has been obsessed with anything paranormal since early childhood.
Among the personas currently implemented in the game, she is a Coward. If Oka sees a corpse or witnesses a murder she will start begging the player to spare her life in exchange for her silence. She cannot participate in physical fights against murderers. It is unknown if she will be given a different personality later on in the game, due to the fact that some rivals may have the Clingy/Damsel persona. Because she is shy, she will hide her face if the player aims their phone at her.
At 7:05 AM, Oka enters the school grounds. She walks to her locker at 7:10 AM and changes from her outdoor shoes to her indoor shoes. At 7:15 AM, she walks to the rooftop and stalks the Basu sisters in search of proof that they are actually supernatural beings, as stated in her Student Profile. If both sisters are dead, she will stay in the Occult Club room instead until class begins.
At 8:00 AM, Oka walks into Classroom 3-2 and sits at her desk. She starts her morning classes at 8:30 AM, and leaves to go to the Occult Club at 1:00 PM.
Oka walks back to class again at 1:30 PM and finishes her afternoon classes at 3:30 PM. She then heads to her locker and lingers there until 3:50 PM, when she heads again to the Occult Club and stays there until the end of the day. If the player joins in club activities, she will unsuccessfully try to summon a demon with the other members from 5:30 PM to 6:00 PM.
If the Occult Club is inactive, she will socialize with the other former members outside of the club when she would normally attend it (1:00 PM and 3:30 PM).
— Talking to Oka.
She is the founder and president of the Occult Club. As with other leaders, the player will have to talk with her to join. If she dies, or less than five members of the club remain, the club shuts down. Any club members who witness the player's crimes will report to her, and Yandere-chan will be either kicked out or unable to join the club. In the future, if the club has disbanded before her designated week arrives, there will be a short cut scene about this, and she will express some very sad feelings.
The Basu Sisters
She stalks Sakyu Basu and Inkyu Basu daily, in a futile search for evidence that they are supernatural beings. This is stated in Oka's Student Profile.
She truly believes that they are supernatural beings, and dismisses any evidence that suggests otherwise.
- Main Article: Senpai
Since she is a future rival, she will have a crush on him and will confess to him on Friday. Oka is a very superstitious person, which might play a role in how she develops a crush on Senpai. Since she is very strange, the way they will meet will be comical.
If she entered a relationship with Senpai, he'd become a paranormal investigator.
- Main Article: Shin Higaku
Oka trusts him to operate the club when she is not present, according to his Student Profile.
- Main Article: Suitors
In the future, Yandere-chan can matchmake Oka with her suitor.
- Oka may walk around in circles, pausing every once in a while, while stalking the Basu Sisters. This can be fixed by bumping into her.
- Oka was implemented in the November 15th, 2015 Build.
- Her favorite "creepypasta" is anything popular on the Japanese internet in the year that the game takes place.
- In November 2015, YandereDev said that one of the rivals may be a student who has anxiety and is always paranoid. This description resembles Oka Ruto.
- Oka's dark secret may be related to the reason for her absence from school for the first few weeks.
- Oka's name is a play on the word "Occult" when transcribed into Japanese Katakana: Okaruto (オカルト)
- YandereDev finds Oka very cute, and has stated that he thinks she is the cutest rival.
- Oka was first created through a suggestion thread. In one of the first "suggestion threads", someone pitched the idea of a goth girl rival. The girl who first popped into YandereDev's head was a shy, cute girl.
- In the future, it may be possible for Oka to be visible as a ghost after she is killed.
- One of Oka's elimination methods may involve the Phantom Girl.
- Oka has played Corpse Party before.
- According to YandereDev, she is "one-third" Hex Maniac from Pokémon X & Y and Pokémon Omega Ruby & Alpha Sapphire, "one-third" Tharja from Fire Emblem: Awakening, and "one-third" Tomoko from WataMote.
- Oka was the only NPC who had a custom walk animation. It was the same animation used when Yandere-chan stands near Senpai. This walk animation was removed in later builds, however YandereDev eventually realized it was missing and re-implemented in June 1st, 2016 Build.
- Since she will currently run away if she witnesses Yandere-chan committing murder, if the latter is a member of the Occult Club she will be kicked out via text message after the school day ends. This may change in the future if she is given a different personality unique to rivals.
- Oka makes a cameo in the Gaming Club by appearing in the stealth game. She is shown stalking Rival-chan and Mai Waifu.
- YandereDev's current reasoning for Oka being absent in the first 3 weeks of school is that she had to deal with some very important personal business.
- Originally, Oka may have been planned to be the fifth rival instead of the fourth, as in the original rival silhouettes, she was placed fifth instead of fourth.
|“||...s-she's...p-probably...a s-special vampire...w-who can survive in the sunlight...t-this requires...f...f-further research...||”|
— Hypothetical dialogue if Yandere-chan told Oka that Inkyu Basu can be spotted in sunlight.
— Speaking to her while she's inside the club.
— Leaving the conversation while she's inside the club.
|“||...y-you...actually...want to join...?...||”|
— Asking to join the club.
|“||...this is wonderful news...perhaps the world isn't such a dark and lonely place, after all...um...anyway...you're an official member now...||”|
— Joining the club.
— Refusing to join the club.
|“||...y-you're not...going to leave us...are you...?...||”|
— Asking to leave the club.
|“||...well...that's to be expected...I mean, who would want to be in this club, anyway....||”|
— Leaving the club.
|“||...oh...that's a relief...||”|
— Deciding against leaving the club.
|“||...we are devoted to the research of supernatural and paranormal phenomena...witches, ghosts, vampires, demons, aliens, psychics, and time-travelers are all welcome here. Anyone who joins our club will develop a resistance to horrific and terrifying things...or succumb to them...he he he...||”|
— When asking Oka about on information of her club.
|“||...um...you can't be...in two clubs at once...I'm sorry...||”|
— Trying to join the Occult Club after joining another.
|“||...the moon is not in position yet...come back between 5:00 and 5:30...||”|
— Trying to participate in club activities too early.
|“||...we're going to attempt to summon a demon again... will you help us...?...||”|
— Asking to participate in club activities.
|“||...excellent...I hope it works this time...||”|
— Participating in club activities.
|“||...oh...well...we can wait...but no later than 5:30...||”|
— Deciding not to participate in club activities.
|“||...I'm sorry...the moon is no longer in position...the ritual can only be performed between 5:00 and 5:30...||”|
— Trying to participate in club activities too late.
|“||...you can't be here...your aura is too dark...you will attract evil spirits...I'm sorry...please leave...||”|
— Talking to Oka after she has witnessed the player murder someone.
|“||...I'm sorry...one of our members believes that you may be possessed by a demon...I can't allow you to join this club...please don't hurt me, demon...||”|
— Talking to Oka after an Occult Club member has seen the player kill someone.
|“||...um...I'm sorry...you can't be a member of this club anymore...you're too scary...huh, that's ironic...being kicked out of a club about scary things...for being too scary...||”|
— Talking to Oka after an Occult Club member has seen the player kill someone while you're a member of the club.
|“||...um... you already left this club once before... I... don't want to let you back in... you might just leave again... and it hurts when people leave... I don't want to be hurt again...||”|
— Asking to join the club again after leaving the club.
|“||..we're about to summon a demon...would you like to join us...?......I can't stop thinking about that boy...I think he cast a hex on me...||”|
— Oka in "Yandere Simulator Rival Introduction Video" 
|“||You're just in time. We're about to summon a demon...would you like to join us...?......I can't stop thinking about that boy...I think he cast a hex on me.||”|
— An alternate line for Oka for the "Rival Introduction Video".
|“||... I've been expecting you... you're here to kill me, right? ... I knew this day would come... but... just so you know... I won't go down without a fight.||”|
— Oka in the introduction cutscene of Yanderetale.