Sa-tsu bako, 茶通箱, tea-through box, ki-ji, 生地, life-ground, unfinished kiri, 桐, paulownia. Box intended for the transport of ma-tcha, 抹茶, powdered-tea. As with any fine Japanese object, it is acquired in a box that can be made of wood of various qualities, or paperboard. Tea, that is a gift, may be presented in a box that is also of various types and qualities. In Urasenke tradition, the preferred box is the Rikyū konomi, 利休好, Rikyū choice, ya-rō buta, 薬籠蓋, medicine-basket lid. It is made of plain wood, ki-ji, 生地, life-ground, unfinished kiri, 桐, paulownia.
The pictured satsu bako is Rikyū konomi. Its measurements are given in kane-jaku: H. 3.75 sun; L. 5.6 x 3.4 sun. According to Chanoyu traditions, these are unusual numbers, as they appear to have no particular symbolism, such as six or eight. However, the width, 3.4, added to the length, 5.6, is a total of 9 sun. The number nine has great significance, as it represents the center radiating out in eight directions, the center of the world. The total sum of the perimeter is 18 sun, and the number eighteen is symbolic of life. There are nine ‘squares’ of tatami in a yo-jō-han, 四畳半, four-mat-half, Tearoom, as there are nine ‘squares’ in the Kon-gō-kai Man-da-ra, 金剛界曼荼羅, Gold-strength-world Wide-weed-gauze.
The top of the box lid is very slightly convex, so that the height of the box varies. The height of the box at the edge is 3.6 sun. The height of the body of the box where it joins the lid is 2.6 sun. the height of the lid is one sun. The ratio between the lid and the body of the box is 3:7. The measurement of the lid diagonally from corner to corner is 6.5 sun, which is the same measurement of the full length of a standard cha-shaku, 茶杓, tea-scoop. At the conclusion of a Tea presentation that uses the satsubako box, the chashaku is laid diagonally across the lid.
The total measurements of the box are width 3.4 plus length 5.6 plus height 3.6 equals 12.6 sun kane-jaku. Transposed to kujira–jaku, the total is 10.08 sun kujira-jaku, which can be expressed as hyaku hachi.
The full height of the box is 3.75 sun kane-jaku equals 3 sun kujira-jaku, which is the same as the length of the standard cha-sen, 茶筅, tea-whisk. Often measurements can be misleading, or may have hidden significance and symbolism.