Kurogane is a fictional character created by the mangaka group CLAMP and appears in their series, Tsubasa: RESERVoir CHRoNiCLE. A ninja hailing from the country of Japan, he was exiled by the princess he served as he constantly killed needlessly. The princess, a powerful seer, sent him to Yuuko, the Time Space Witch, and placed a curse on him: every time he needlessly killed, he would grow weaker and weaker. To pay for travelling across dimensions so he could get back to Japan he reluctantly gave up his sword Ginryū.