Kazuto Tonooka holds the rank of B-rank Sniper in Border's Yuba Squad. Initially described as plain and difficult to distinguish, his appearance was transformed when the squad's operator, Nono Fujimaru, gave him a flashy punk-style haircut to ensure his skills would not be overlooked. This new look became his standard appearance.

He enjoys kashiwa tempura, roasted green tea, and spending time alone.

His given name, Kazuto, is written with kanji that literally mean "one" and "to," an obsolete liquid unit equal to 18 liters. His family name, Tonooka, translates to "hill exterior."