Tokyo is expected to send a shipment of ancient Korean royal books back to South Korea as early as next week, a diplomatic source said Friday, about a year after Tokyo agreed to their return after they were seized from the Korean Peninsula during the 1910-45 colonial rule. \"To my knowledge, both sides have set Dec. 1 as the date for the handover and consultations on details are under way,\" the source said on the condition of anonymity. Last November, Japan agreed to send back the books amid moves by the two nations to improve relations. Tokyo completed its required domestic legal process to return the books by Dec. 10 at the latest. On a visit to South Korea last month for summit talks with President Lee Myung-bak, Japanese Prime Minister Yoshihiko Noda carried some of the promised books with him. The books include texts of royal protocols known as \"Uigwe,\" all of which are being kept by the Imperial Household Agency in Tokyo. Uigwe is a collection of documents from the Joseon Dynasty (1392-1910) that records and illustrates procedures and formalities used for weddings, funerals, banquets and receiving foreign missions, as well as the cultural activities of the royal family. Relations between South Korea and Japan have often suffered setbacks due to territorial and historical rows related to their colonial past, as Tokyo has attempted to glorify its militaristic history and also lay claim to South Korea\'s easternmost islets of Dokdo.