Kazuma is Motoki's half-brother. The Yaze family held a strong bias against Kazuma, an illegitimate son. Having been scorned throughout his childhood as a lackluster Hyper Adapter, Motoki related to him on some level, and gets along well Kazuma.
Akishige Yaze was Motoki's father, and the head of the Gigafloat Management Corporation.
Asagi is Motoki's childhood friend. He is aware that Asagi has a crush on Kojou, and often teases her about it.
They met and became friends during middle school. Unknown to him, Motoki is the true observer of Akatsuki Kojou.
Koyomi is one of the three saints of the Lion King Agency, and is also Motoki's girlfriend.