榷 - く

Japanese: 榷 - かく

…In the case of seaports, it is called Goshibo or Shibo. As the synonyms Kaku and Kakujo are used, it was originally a passive, defensive trade that played the role of a monopoly, economic blockade, national isolation, and checkpoint. After the Song Dynasty, when China's economic power was strengthened and the power of neighboring countries also improved, horses, silk, tea, precious metals, copper coins, furs, and incense medicines were exchanged only in the Goshibo, and it played the role of peacefully appeasing external pressure and maintaining diplomatic balance. …

From [Exclusive]

...This resulted in the abolition of the tobacco monopoly that had existed for about 80 years since the Meiji era. Tobacco Tax [Katsunobu Takeuchi]
[China]
In China, from the Han dynasty onwards, monopoly was expressed with the character 榷 (kaku), and 榷茶, 榷塩, 榷酒 (酤 (ko)), etc. all referred to the monopoly of tea, salt, and alcohol. The original meaning of 榷 was a solid log bridge, one-way traffic for one person, meaning a monopoly on profits.

*Some of the terminology explanations that mention "榷" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…海港の場合は互市舶，市舶という。同義語に榷（かく），榷場（かくじよう）と表現するように，もともとモノポリー，経済封鎖，鎖国，関所の役目を果たす消極的･防衛的な貿易であった。中国が経済力を充実し，周辺諸国の実力も向上した宋代以後，馬，絹，茶，貴金属，銅銭，毛皮，香薬などを互市場に限って交換し，外圧を平和裏に懐柔して外交の均衡を守る機能を果たした。…