| 鬼子母神 陽子'|
|Occupation:|| High School student |
|Voice actor:||Ayako Kawasumi|
Yoko's father, Koji Masuda, is an explorer who teaches archaeology, and her mother is an expert in Kishibojin-ryu Jyujutsu. At age 10, her parents divorced, leaving her to be raised solely by her mother. Although still in high school, her talents in Jyujutsu have been acknowledged by the ICPO (Interpol) which enable her to participate in their hand to hand combat research team. One day, she received a letter from her estranged father, entrusting her to carry out the duties necessary to acquire Ehrgeiz. In addition to this, she has been ordered by the ICPO to enter the tournament to investigate suspicious activities surrounding Ehrgeiz.
In her ending, Yoko gains the Ehrgeiz sword after she defeated the Red Scorpion as she quickly runs to escape only to be confronted by Dasher Inoba who is one of the members of Ehrgeiz supervising committee who wields a giant axe and both fighters are clashing with their weapons until Inoba slams his axe to the stone floor bridge which Yoko avoids from falling into the edge by hopping backwards. Without warning, Inoba goes for a final strike by impaling her with his own axe. But it doesn't reach her as he falls into the edge below. Yoko looked at the bottom to see Inoba is hanging with both of his hands which he does not want to get himself killed from falling into the edge and Yoko childishly taunts him by showing her tongue several times.
Yoko appears to have a long brown hair with a full fringe and is tied in a high ponytail. Her face strongly resembles her estranged father, Koji Masuda and brown eyes.
Her primary appearance, she wears a dark gray combat vest with the sign "ICPO" at the back of her vest with a light blue short sleeved button shirt with ICPO insignia in each side of her sleeves, dark blue shorts with a black belt to her waist, dark blue socks and a matching dark gray combat shoes. She also wears a matching dark gray fingerless gloves and wields the red spiked yoyo on her hand.
Her second outfit is her school uniform from the Ehrgeiz opening, which she wears a white short sleeved sailor fuku which is tied in a sky blue bola tie and the color of her fuku and the edge of her short sleeves are dark blue with two white linings, dark blue skirt with black panties underneath, white socks and black and white sneakers. She also wears red gauntlets with gray metal designs.
In the Ehrgeiz opening, she only wears a red wristband on her right wrist and maintains wearing her left red gauntlet with metal designs.
In her CGI appearance, her bola tie on her uniform is red instead of sky blue.
Yoko appears as a strong and determined girl who can seriously take down her opponents but is also an energetic and childish person as seen in her ending trying to taunt at Dasher Inoba by childishly showing her tongue for being a loser after he almost impales her with his giant axe to make final strike towards her. She actually inherits her estranged father's strong personality who had a tough streak, seriousness in fighting and his fighting spirit. Yoko still maintains her respect to her estranged father after he gives a letter to her about to carry out the duties in acquiring the Ehrgeiz.
Yoko's fighting style are more focus on kicks with a bit of punches unlike her estranged father Koji who is more focused on both punches and kicks as well as utilizing break throws. She also seen makes a triple flying kick towards her opponent with a critical damage, a combo with a reverse backflip kick and lastly with a flurry of straight kicks. Her unique ability has her to ensnare her opponent with her red spiked yoyo to make a quick attack towards them with her moves but once during charge it also enables her to spin her red spiked yoyo to hit her opponent three times. She also has a special ability is to throw marbles towards her opponent in order to slip them to make a damage even to herself as well.
- Yoko wears both of her outfits in the Ehrgeiz opening.
- So far, Yoko is the only character who currently gains the Ehrgeiz sword as seen from her ending.
- In the Ehrgeiz opening during a clash between Dasher Inoba with weapons, she wears her school uniform. But in her ending is her ICPO primary outfit.
- When executing her red spiked yoyo, it shows in a rainbow fashion and its ability like any other professional yoyo experts, they mostly use the walk a dog skill.
- Her fighting style is based on both Paul Phoenix and Marshall Law from the Tekken series despite her fighting style is Kishinbojin-ryu Jujutsu.
- She actually gains Paul's PK Combo and Double Hop Kick High and Marshall's Somersault Kick and his Straight Kick combo from the previous games.