Yoko Belnades is a member of that family of legend, a gifted magic-user descended from Sypha Belnades and even Carrie Fernandez. Because of her great magical powers, Yoko became another in a long line of witches to find employment with the Catholic Church. Yoko and her employers knew well of Nosatradamus' prophecy that in the year 2035 a new master would locate the haunted Castlevania and inherit the estate and all of Dracula's powers with it. Fearful of this event, the Church sent Yoko out to investigate matters surrounding the predicted event and any ties to the Hakuba Shrine.

Because her family grew closely together with those representing the Belmont clan, she knew of Julius Belmont's past exploits and to where the castle was banished. This knowledge, she thought, made her an expert on the matter. Once she was able to transport into the castle, along with Genya Arikado, further investigation led her to believe that the prophecy was true, that someone would inherit Dracula's power--but she was tracing the wrong subject. After the talkative and noisy Yoko befriended Soma, she shared with him her evidence that Graham Jones was to be the recipient of Dracula's dark power. She couldn't know how wrong she really was.

When Graham caught on to her presence, she became a target of his increasing insecurity. When they met up in the castle's catacombs, he attacked her viciously, stabbing her in the chest. Soma arrived in time to scare him off before he could finish the deed. By the time the truth was revealed, that Soma was the subject destined to inherit that dark power, Yoko was too hurt to offer any assistance. Instead, she mustered what energy she could to participate in the psychic contact with Soma, to do her part in offering the words of encouragement that would see him finally conquer his inner demons.

One year later, Yoko was involved in the Church's investigation of the new cult headed by Celia Fortner. Joined by Julius Belmont, she headed to the cult's hideout to aid in eliminating the threat. Neither wished for Soma Cruz to become involved in the matter, but his determination was evident. While Julius understood why Soma would take such measures, Yoko could not. Then again, Belmont has his own agenda, and he infiltrated the cult's hideout, ditching Yoko at its entrance. She had no choice but to request that Soma escort her to the safety of a nearby village.

Back at the village, realizing that she now had little control over the continuing investigation, Yoko set up a shop in order to teach Soma about the importance of magic seals, which could be used to draw in dark power. She would also assist in his mission with a process of "weapon synthesis," wherein she would fuse together weaponry and spared souls in order to create for him new tools of destruction. Furthermore, she would provide inside information, when necessary, on a myriad of topics. Though leery of Hammer, who set up his own shop across the way, Yoko was happy in this role. And when the battle was over, the cult having been defeated, Yoko was one of the first ones there to greet the victorious heroes.