Kafuin manifests as a crotchety old monk of the Way of Light. Shizumaru decided to emplate him on Kafuin Nikochin, the late master of his own sensei, Haohmaru. Kafuin is a bit whimsical, at times, but takes his duties quite seriously.
Recently, Kafuin was zapped by the Gloom Device when it snatched Shizumaru to another universe; his attempts to fight it got his CPU fried and accidentally flung Rimururu to a random shadow. Nagisa has completed repairs on him, and he is now the same as ever.