Krad

Krad is an entity similar to Dark, living inside his "tamer" Satoshi Hiwatari. He is Dark's opposite in many ways, including his name ('Dark' spelled backwards), having blond hair, wearing white attire, and always speaking very politely using an extremely formal speech pattern. He is an entity of unknown origin who has appeared in the Hikari family for the last 400 years (300 in anime).