Unlike other Box Weapons, the White Dragon is made fully of Dying Will Flames, even though it's white.
It was made with the highly advanced technology of the Millefiore Famiglia and is exclusively for him. When the Dragon is released from the Box, it is seen attached to Byakuran's hand.
Byakuran also used a miniature version of the White Dragon in an attempt to pierce Tsuna's heart. However, Tsuna was protected by Lancia's Boss's Ring. The Dragon is a small white dragon with Sky Flames covering it. It has long sharp ends.