He is the commander of the fifteenth armoured division 'Rozen Maiden' whose symbol is a three-leaf rose.

Also, he is the nephew to the emperor of the - jet unnamed - eastern country. He is called 'Shinka' or 'Sakone no Daishou' (which roughly means 'Commander of the left imperial guard')

Taki appears as a calm but sometimes passionate commander, but when he's alone with his knight - Klaus von Wolfstadt - he shows a pretty weak and breakable personality.

(Source: maidenrose wikia)