Kozaru

Kitsunesaru is an Assassin from D.D.D.

Fallen Guardian arc
Yuta and Kitsunesaru accompany Rieze to the Watermaple Consulate Raid Party's training grounds to help Akatsuki learn an Overskill. After they knock her down during training, she pushes herself up and tells them to have another go, causing Yuta to look at Kitsunesaru questioningly, who just sighs.

Trivia

 * Kitsunesaru is one of the D.D.D members that comes from D.D.D Diaries.