Rugui has an unkempt appearance and wears an eye-patch.
He is described as having a stern personality. He is the one who mainly makes Makoto's main equipment related to sealing and absorbing Makoto's immense magical power. He is dumbfounded by the fact that the items which he makes ends up obsolete to contain/absorb Makoto's magical power as when these items are equipped by a normal person, they would die. Thus he is committed in developing new equipment which can kill Makoto for sure, which ends up worrying Makoto.