In the past tea was stored in big jars known as Chatsubo. These jars had bags of Koicha hanging in the middle, and they where stuffed with Usucha around to protect the koicha. They where traditionaly opened in November, in a special chaji called Kuchi Kiri. Today fresh tea can be aquired at any time, and the tsubo has lost it's most common use. Still Tsubo Kazari is one of the 16 Konarai temae that student learn. This temae is part of the Kuchi Kiri chaji.
An Oni Shino tsubo by Tsukigata Nahiko