The attendant that came with Kanami Ibuki to Wet Crow's Feather Island as her caretaker: Shinya Sakaki. A friendly man that assists Kanami when needed, though she can be stubborn. He cares for Kanami greatly, yet does speak ill of her personality towards others. He considers himself and Ii to be similar as they both aren't geniuses and are companions of actual geniuses, though the similarities end there. Originally, Shinya was the one that taught Kanami how to paint after her vision was restored.
As Akane and Kanami switched places, Shinya knew and was assisting Kanami, now acting as Akane, with her plans. In the end, he helped the real Kanami escape the locked room and didn't care if others died. Jun Aikawa states that Shinya has likely been with Kanami for a long time, and has been with her even before she claimed the original Kanami's identity.