Mitsukado Youko is the sole granddaughter of Mitsukado Youzan, and the overseer for the Mitsukado Zaibatsu. She is also the youngest member that participated in the Destroyal.
Youko is a beautiful young woman with white flawless skin, a slender figure, and long straight hair styled into a hime cut. She is usually seen wearing long dresses and hats. Youko usually has a cold, haughty, and authoritative demeanor. When angry or stressed, she often tenses up delivering what could only be described as a death stare. This is often accompanied by intense blueish, shrunken pupils, gritting of the teeth, and homicidal thoughts.
Youko has a firm handed and stoic personality. She sees the Killing Bites Destroyals as a professional game of wits and takes it very seriously. Youko sees no reason as to why nobodies like Nomoto Yuuya should be allowed to take part; as she thinks they will lose from inexperience making a joke of the competition. She is focused and logical in her thinking, planning carefully, and with her main goal being to crush her competitors.
Physically, Youko doesn't seem to know any martial arts. She is however very intelligent and seems to be a very experienced player during the Destroyal. This is evident in her strategies and insights during the game. She is keen and observant and can usually tell what her opponents are thinking about.
After losing the Killing Bites tournament to the Ishida Zaibatsu, a distressed Youko went to the VIP lounge to face her grandfather only to find him dead. Horrified and devastated, she then discovers the betrayal of the Bureau and both the Ishida and Yatsubishi Zaibatsus. Enraged, she orders Leo (Yugo Tani) to slaughter the traitors but was further shocked to learn that he is actually one of them and that he had betrayed her.
Thoroughly defeated and helpless, Youko is then approached by Leo who asks her what's it like to be a pawn in someone else's game, just like how she treated the lives of the Therianthropes. As a final stand, Youko angrily brands him as a traitor and was answered with an attack that landed narrowly beside her head. Nevertheless, Leo spares her and offers to let her live as his slave if she "watches her mouth and pays him the proper respect".
Youko is last seen subjected to being raped by her former ally and bodyguard, her fate left in the hands of her grandfather's killer.
- Youko believes her grandfather has been corrupted by Shidou Reiichi imprisoning his heart. She has a flashback to her father overseeing the death and gore in the Destroyals with pure sadistic delight.
- Youko is determined to reform Mitsukado Youzan, bringing back the kind loving grandfather she used to know by making the Mitsukado Zaibatsu victorious.