Kuniharu Kakizaki/Plot

Background
Kakizaki joined Border during its debut 4 years ago. He was at a press conference with his teammate at the time, Arashiyama, regarding Border's recruitment of new members. When asked whether he would protect his family or fellow citizens (only one of the two), he chose what he believed to be the safer answer: citizens. When Arashiyama Unit became the PR unit, he decided to leave because he didn't feel worthy to be a part of it. He was introduced to Madoka Ui, and then recruited two prodigies, Kotarō Tomoe and Fumika Teruya.

B-Rank Rank Battles Arc
When Yūma is lost in the halls of HQ, he guides him to the Rank Battle place. He reveals that his team is one of Tamakoma Second's upcoming opponents. When Kako asks for Yūma to join her unit, he shows visible surprise.