Sen-ryo-bako (literally, a box to store 1000 ryo; a box to store a lot of money during the Edo perio (千両箱)
Sen-ryo-bako was a box exclusively used to store a large amount of koban (former Japanese oval gold coin) during the Edo period.
Summary
As the name indicates, it was a box to store 1000 ryo, and a sen-ryo-bako was just enough to hold 40 koban or 40 wrapped lumps of ichi-bu-kin (a kind of gold coin) (equivalent to 25 ryo). From around 1854, other types of sen-ryo-bako such as those exclusively used for ni-bu-kin (a kind of gold coin) or those possible to store oban (former Japanese biggest oval gold coin) were also began to be used. Furthermore, go-senryo-bako (literally, a box to store 5000 ryo) and man-ryo-bako (literally, a box to store 10,000 ryo) were also derivatively made and used.
Many of these boxes were made of Japanese cypresses or oak, and the corners were reinforced with iron plates. There was a type of sen-ryo-bako which could be locked with a padlock. Although there were various sizes of boxes, the most ordinary type to store 1000 ryo was 40 cm long, 14.5 cm wide, and 12.3 cm deep.
Legend
We often see a scene in TV drama in which a thief like 'Nezumi kozo' (a Japanese thief and folk hero during the Edo period) are jumping over from one roof to another with a sen-ryo-bako under his arm, however, because a box full of koban of 1000 ryo often weights more than 15 kg, it is difficult to run and jump to escape with it under his arm.
Incidentally, there are hands-on spots where one can actually experience to lift a sen-ryo-bako with the equivalent weight of the real one at the Edo Tokyo Museum in Sumida Ward, Tokyo and the Mint Museum in Kita Ward, Osaka City.
Sen-ryo-bako in modern age
Even now, boxes to store gold bullions (ingot) or bullion bars are sold at noble metal trading companies as "sen-ryo-bako" (sometimes such boxes are offered to purchasers as free gifts). Such boxes are the imitation of sen-ryo-bako in the Edo period, and they can store valuable goods from millions to tens of millions of yen (currency).
Furthermore, some pachinko parlors also prepare wooden boxes printed "sen-ryo-bako" on them, and those boxes are used to store pachinko balls or coins (medals) which players earned. Balls or coins are stored directly in the sen-ryo-bako or a box full of balls is stored (to prevent balls from spilling out of the box when they are transferred to another box). Because the box is not intended to be used for storage but to appeal the amount of balls to other customers, it has no cover and its inside can be seen directly.