Ruko Hakane (るこ はかね) first appears in episode 1 where she says "hi" to Sakura-nyan. Then she is in episode 3 where it is releaved that she is a mahou.
She is a nice girl and is older than the other mahous and very respectable.
It is also heavily implied here that Yukiko is going to be involved in a relationship of some sort with Ruko.
She is voiced by ShintaroKisaragii.