|“||Cityscape A...?! That is, like, a super-standard map! Like... a really normal place! I thought we needed to find a way to counter Tamakoma's wires!||”|
Kashio is a light-skinned boy of medium build. He has short, straight, dark hair with a middle part and choppy bangs, thick eyebrows and almond-shaped, vaguely blocky eyes with big, dark irises.
Kashio's uniform is comprised of a black double-breasted jacket with a Korean collar and plain button epaulets. The jacket is fastened by a row of seven square buttons. Kashio keeps the collar open, revealing the collar of a white shirt underneath. The sleeves are rolled so that the three parallel stripes, two whites and a central, thicker light blue one, on the inner portion of the cuff is visible. Two angular pockets with a blue stripe at the top are sewn on the chest, one on either side of the central row of buttons. The B-rank logo is emblazoned above the left pocket. The attire is completed by black pants with front and back angular pockets which are rolled just above the matching black boots, reaching halfway up Kashio's shins.
Kashio is stiff and very formal when speaking to his superiors, a consequence of being raised to address his own parents in the most polite manner. He can work himself up quickly when his expectations are not met, although he will calm down just as easily when given an explanation. He has a keen sense of responsibility and is very serious about his studies.
Kazuaki Ōji and Kazuki Kurauchi address Kashio by his nickname, without adding honorifics. The three of them and Haya Kittaka have become very competitive about chess after being introduced to it by Ōji, and they all practice in secret.
- (To Kazuaki Ōji) "Cityscape A...?! That is, like, a super-standard map! Like... a really normal place! I thought we needed to find a way to counter Tamakoma's wires!"
- "It was my mistake that I lost sight of Mikumo. I will definitely take down both of them...!"
- Kashio likes lasagna, ramune (a Japanese soft drink), potato salad, and studying.
- Kashio's nickname, whose katakana have the same pronunciation as the hiragana in his surname, is a pun based on the electronics multinational Casio.
- The same pun is at the heart of Kashio's icon on his unit's monitors, which is the face of a Casio watch with Kashio's bangs.
- He is a student council president at a private middle school and a senior to the members of Kōda Unit.
- The author revealed that Kashio had never experienced failure until he was bested by Ai Kitora in combat, and wondered if the defeat caused him to develop a crush on her.