Although she has a cheerful and determined personality, she also has a girly side and likes older men. Yoko is well aware of having admirers in STORAGE and challenges them to an arm-wrestling match that she usually wins, which she does because her father told her not to marry someone weaker than she is. After being rescued by Ultraman Z from Neronga, she had become infatuated over the giant, never minding the fact that he is 5,000 years old. She also worries whether humans should wield the power gained through the various over-technologies such as King Joe STORAGE Custom or D4. Yoko also acknowledges that while monsters have no place in the world, it is ultimately because of humans, and wants to bear the weight of that by taking the responsibility of dealing with them.
Yoko was first seen piloting Sevenger against Gomess, where she accidentally caused the robot to topple against a building to avoid stepping on Haruki Natsukawa. When an extraterrestrial monster attacked, she was instructed to evacuate civilians from the evacuation center, Shinkoyo Elementary, aiding Haruki in Sevenger and Ultraman Z. After the monster was defeated, she chanced upon the Ultraman Medal, and soon met up with Haruki.
Nearing to the finale, Yoko was possessed by Celebro in order to pilot Ultroid Zero, using her and the robot, Celebro traveled around the world absorbing various Kaiju to evolve Ultroid Zero into Destrudos. Haruki had to rescue her using King Joe STORAGE Custom, and managed to free Yoko from Celebro's influence by beating her in an arm wrestling match. She helped Haruki transform while falling from the sky, and later cheered on Z and helped him defeat Destrudos. After the battle, Yoko and the other STORAGE members said goodbye to Haruki as he departed into space with Ultraman Z.
- Powers and Weapons
- Strength: Although the exact limit of this is unknown, she is the undefeated winner of arm wrestling matches against men, some of which being her admirers in STORAGE. The first and only person who has defeated her so far is Haruki.
- Piloting: She is the ace pilot of SAA units, with Haruki being her partner on missions.
- Beam Rifle: Whenever she is out of piloting in ground missions, Yoko carries STORAGE's beam rifle as her main weapon.
- Kaiju Medals (怪獣メダル Kaijū Medaru): A set of medals created by Celebro from reverse-engineering the Ultra Medals.
Ultra Medals in Possession
- She has little tolerance for the cold.