Yukio

King Yukio is the ruler of the Land of the Collseum. He sits in the royal box behind bulletproof glass during Kino's participation in the tournament.

Seven years before Kino's visit, King Yukio murdered his father by posioning him. To cover up his deed, he murdered the doctor presiding over the late king, and replaced all the ministers and courtiers. He also set out to eliminate his own family to prevent an uprising via execution or exile. His wife killed herself from the grief, and their only son vanished, his fate unknown to the countrymen.

He began to run the country with arbitrary laws, and implemented the tournament when citizens began to flee the country - declaring that only those proven most worthy may become citizens.

Yukio's son, Shizu, returns seven years later to join the tournament in hopes of killing his rather. Yukio is killed by Kino when they shoot a bullet at him with the mock intention of killing Shizu.

(Source: Kino's Journey Wiki, edited)