Annan-fu (安南都護府) an old geographical area of SE China - northern Vietnam - term used during the Tang Dynasty (618-907 C.E.) - Karakusa-mon/唐草文/arabesque design tokkuri
The small size of this tokkuri might be because it was made/used for the tea ceremony. According to Yanase this is an early piece of Rosanjin's work probably made around 1925. Tomobako signed by 2nd generation Kuroda (二世黒田陶々庵箱) to authenticate this piece. 唐草文を全体に描いた可愛らしい徳利です.

Kitaoji Rosanjin was born in Kyoto to a family in the service of the Kamigamo Shrine. Abandoned by his natural mother and raised by a foster family, he became interested in art early in life. At the age of ten Rosanjin was impressed by the power of a calligraphic restaurant sign carved by Takeuchi Seiho (1864-1942) and an exhibition of Seiho's work further inspired him. Rejected by the Kyoto Municipal Art School, Rosanjin nevertheless won a local calligraphy contest that gave him encouragement and, by the age of twenty, he had become an accomplished signboard carver, a skilled calligrapher, and he had achieved mastery of archaic Chinese seal engraving. 

In 1915 at the age of thirty-two, after holding calligraphic jobs in Tokyo and traveling in Korea and China, Rosanjin returned to Kanazawa and studied ceramics under the direction of Suda Seika for two years. In 1917 he moved to Kita Kamakura, established a kiln, and remained there for the rest of his life. 

From 1925-36 Rosanjin was the advisor to the Hoshigaoka restaurant located near the Sanno Shrine in Tokyo. The patrons of this gastronomic institution were the city's industrial and political elite, who came for the finest cuisine Tokyo could offer. Rosanjin, an epicure, designed all the ceramics used in the restaurant. After eleven years he was relieved of his position due to his famously cantankerous personality. He continued to live and work at Kita Kamakura and left Japan to travel extensively in the West only once, in 1954, when he exhibited work in Europe and in the United States.

 Rosanjin's genius defies classification. His broad talents encompass the disciplines of ceramics (including his stylistic interpretations of Shino, Seto, Bizen, Oribe, Shigaraki, Karatsu, Iga and Kenzan wares), calligraphy, engraving, and painting. He brings a unique expression and his own vivid personality to each form. He was one of the few potters to reject the government designation of Living National Treasure (LNT) in 1955 and 1956.
See: Frederick Baekeland, ed., Modern Japanese Ceramics in American Collections, pgs. 101-102, 122, 139