Jokisen is a brand of Japanese green tea. High-quality tea produced in Uji. Its original brand name of green tea is Kisen and the fine quality tea is called Jokisen (or Shokisen).
The brand is famous for the kyoka (comic [satirical] tanka) that played on words associated with the arrival of the Black Ships (jokisen [steamboat] in Japanese) by Matthew Calbraith PERRY, 'Jokisen is such a good tea that you have trouble sleeping at night with just four cups and rouses you from your quiet long sleep.'
The kyoka was a satire on the dismay of bakufu (Japanese feudal government headed by a shogun).