Because the family was started in Kira no sho Isshiki in Mikawa-no-kuni (present-day Isshiki-cho Hazu-gun Aichi Prefecture), they gave themselves the surname Isshiki.
三河国の吉良荘一色（現・愛知県幡豆郡一色町）から起こったため、一色姓を名乗った。