Wilhelm "Sagiri" Kurosaki

About

Sagiri is Shigure's older brother. Seemingly cold and emotionless, he insists his brother is unfit to be a bodyguard and takes over the position of guarding Rei in volume 4 for the moment at least.....

He was Rei's bodyguard before he got hurt in an incident involving Rei. Shigure took over until Sagiri could heal.

Yuji seems to have an interest in him in volume 4.

sources:
Our Kingdom manga