Ryoko is a teenage Japanese girl who is just entering university. She has a svelte body and is of small stature, being more than a head shorter than Hol Horse. She has long hair pulled back into a short ponytail and a braid running along the side of her head. Ryoko also has a notable twisting bang on the right side of her face. Like Noriaki before her, she wears a single cherry earring.
Ryoko wears a light shirt with short sleeves, a dark necktie, a long dark skirt with a large dark belt that covers her whole abdomen, and loafers with spotted socks.
Ryoko is shown to be attached to her cousin Noriaki Kakyoin and to his memory. Even ten years after his death, she takes the time to visit and mourn over Noriaki's grave just before the academic year begins. After Noriaki's death, she tried researching to understand the cause and found incidents that may have some connection, like senator Wilson Phillips dying on the same day. According to Tohth, Ryoko hasn't moved on from her affection for Noriaki. She has styled her bang after Noriaki's and when Josuke Higashikata mocks Noriaki by misnaming him maliciously, she slaps Josuke without thinking.
Ryoko displays a rather contemptuous personality although she remains mostly polite. When confronted with a thug who publicly causes trouble and tries to antagonize an old woman, Ryoko calls him "so evil that she can see it clear as day". She also subtly teases Josuke about his hairstyle, asking him if he was trying to replicate a character from the movie Blade Runner with his unique pompadour and trying to correct him when Josuke mistakenly calls him a "high school girl", wanting to remind him that she is his senior. Josuke calls her out on her "holier-than-thou" and aloof behavior.
She hates cloudy days because she can't see the sky. Ryoko is not afraid to stand up for others and selflessly protects an old lady from a thug. She acts maturely according to others, though she personally thinks she hasn't changed much on the inside. Josuke dislikes her 'cool' attitude, thinking that Ryoko gives off the impression that she is better than others.
At some point in 1988 when Ryoko was seven years old, she went on a family vacation to Egypt along with her cousin, Noriaki Kakyoin. They encountered DIO in Cairo. Ryoko apparently escaped DIO's notice by hiding behind some planks while the Vampire confronted Kakyoin. She managed to safely return to Japan with her family but then Noriaki vanished, only for his corpse to be found in Cairo.
In March 1999, Ryoko has just gotten admission to a university. Before the academic year begins, she goes to Morioh to pay her respects to Noriaki's grave. A bird suddenly flies above her and she has a vision of DIO apparently trying to seduce her to his side. When she returns to her senses, she tearfully asks why Noriaki "disappeared" from his family's lives.
Going back to town, Ryoko calls someone to inform them of her whereabouts and says that she plans on staying in Morioh for several days. While walking, she spots a strange comic book on the ground and picks it up. Skimming the pages, she sees a line predicting that Hol Horse will see DIO. The sight of DIO's name makes her recall a scene of Noriaki obeying DIO's orders. Someone approaches and Ryoko takes the book with her, hiding it in her bag. She then passes by Hol Horse himself while walking away with the book.
Later, Ryoko takes out Boingo's book from her bag and contemplates taking it to the police. She thinks back to how Noriaki vanished after returning to Japan without saying a word to his family and then his corpse was found in Egypt. When she thinks that the book could have had something written about Noriaki in it, new pages showing Josuke start to emerge.
A thug parks his car in the middle of the road, blocking the way for other drivers. An elderly lady walks up to him and asks if he can move his car but the thug furiously tosses his phone at her, asserting that she made him miss part of an important call. Ryoko walks in front of the old lady and deflects the phone away with her bag, breaking it when it hits the ground. She tells the man that although he's clearly evil, he'd be better off parking somewhere else. Infuriated, the man yells at Ryoko for breaking his phone and asks if she's one of Fungami's girlfriends. However, the thug's girlfriend comments that Fungami only likes pretty girls.
The thug insults Ryoko's dangling hair, claiming Fungami wouldn't give the time of day to someone like that. Ryoko then smirks and asks if he was talking to the boy behind her, pointing out Josuke. Instantly, Josuke rapidly punches away the thug's car with Crazy Diamond, reshaping the roof of their car into a cage. Hol Horse apologizes to Ryoko for Josuke's behavior, asking if she got hurt anywhere. Ryoko thinks back to the pages she just read in the book, amazed that its predictions came true.
Conflict with Josuke
Tohth describes how Ryoko thinks she hasn't changed at all since she was seven years old despite people calling her really mature. After all those years, she can only think about her cousin and wants to know why he got killed no matter what. The book also reveals that Josuke is the key to solving the mystery, and Ryoko wonders how a delinquent could help her like that. Josuke calls out to Ryoko, angry that she indirectly insulted his hair as well. In response, Ryoko asks Josuke if he based his hair on the Nexus-6 model replicant lady from Blade Runner since it doesn't look like a standard pompadour. Josuke doesn't understand and asks her to clarify whether that's an insult or compliment. However, Hol Horse interferes and says Josuke should cherish ladies instead of threatening them.
Hol Horse asks Ryoko if she can understand his Japanese properly. Although he would like to apologize by taking her out for dinner, he has business to take care of. Ryoko is confused, but Josuke explains how Hol Horse got separated from someone he came to Japan with. Hol Horse describes how Boingo is short and was carrying a comic book, asking if Ryoko saw him anywhere. Shocked, Ryoko clutches her bag with Tohth inside and hides it behind her. She tells Hol Horse that he should ask at the kōban (neighborhood police station).
After Hol Horse leaves, Ryoko takes out Tohth again, realizing it must be the book Hol Horse mentioned. She doesn't want anyone to take it away from her until she learns the truth. New pages then emerge, telling Ryoko to slap Josuke in the face in order to learn the first hint toward Noriaki's death. Josuke interrupts while she's reading by grabbing her hand and yelling at her since he doesn't want his grandpa to see them. He asks why she's still following them and tells her to leave. Amused, Ryoko asks Josuke whether he's trying to avoid his grandpa while he's on police duty. Josuke doesn't like her tone and calls her a highschooler, causing Ryoko to explain how she just graduated from high school in spring and is only wearing her uniform because was visiting a grave. She calls Josuke a hypocrite for wearing his uniform already when he won't even be in high school until next month. Josuke rants about how Ryoko talks like she's above everyone else and asks which actor Ryoko copied her hairstyle from. Ryoko ends up slapping Josuke for insulting her cousin, but Josuke smiles in response. He thinks this attitude fits her much better and asks Ryoko if she feels relieved now.
Approaching the Truth
Ryoko is astonished that she actually slapped Josuke for making fun of Noriaki, and remembers that Tohth predicted that she would also kick Josuke in the butt next. Josuke asks why Ryoko doesn't go to Noriaki for help if something's troubling her. Ryoko thus reveals that he passed away, causing Josuke to awkwardly apologize. Just then, Josuke acts as if he's heard a gunshot but Ryoko hasn't noticed anything.
Ryoko suddenly sees one of the possessed chefs charging toward them with a knife and kicks Josuke out of harm's way, fulfilling Tohth's next prediction. Ryoko then witnesses Josuke dispatch the group of crazed women as the chefs are hit by an invisible force near Josuke. The women regain their senses, being confused but also unharmed for a reason unknown to Ryoko. A police officer arrives on the scene and asks Ryoko what just happened there, to which Ryoko claims she didn't see anything.
Ryoko discreetly follows Hol Horse and Josuke and eavesdrops on them talking about their Stand powers. She hears Hol Horse reveal that there is a parrot in town who possesses a Stand and was trained by DIO. Ryoko realizes that this is the hint Tohth promised her and that Hol Horse knows something about DIO. She consults Tohth to know what to do next and the book warns her that she cannot openly pry Hol Horse about DIO or else he will simply play dumb. The best thing to do is look for a fuse waiting to be lit and then ignite it. After that, she'll finally reach the truth while everyone is screaming from the explosion.
- “I saw a bird. It was there the day I lost someone very important to me, in Egypt… Like an astute observer, trying to note every event that happened below… it was circling the sky.”
- “I got into university. I can't believe it’s been 10 years since you left us…”
- “What do you call that hairstyle, I wonder? It's not exactly your standard pompadour. Perhaps you based it on a 'replicant' from Blade Runner. There's a Nexus-6 model in the movie with a similar hairstyle... Even though she's from the future, her hair's still got a classic feel to it. That's Ridley Scott's specialty as a director... Is that what you were going for?”
- “Don't you dare make fun of my cousin Noriaki.”