Constellation:

Character:

Ichiru Kiryu is Zero's younger twin brother. When they were younger, they were both taught by Toga Yagari to become vampire hunters. Ichiru, however did not seem to share Zero's natural ability and was often ill. Zero and Ichiru were very close as children, although later Ichiru claims to have hated Zero after overhearing that his parents preferred Zero over himself.

Source from Wikipeida