"GOLDCASTLE (GOLD CASTLE) HAND PAINTED (HANDPAINTED) CHIKUSA MADE IN JAPAN"
According to Carole Bess White, the Goldcastle mark belongs to Tashiro Shoten Ltd located in Nagoya, Japan. Other names used by Tashiro Shoten are "Trico", "Trico China", "Royal Trico", and two logo marks: Elephant with "MADE IN JAPAN" below and "TA" within a cherry blossom flower.
Information provided by Waiapo.com