Prior to the use of mechanical clocks in Japan, timekeeping was a task performed by monks in Buddhist temples and Shinto shrines, and the hours were struck on temple bells. During the day sundials could be used to determine the time and at night, astronomy. However, when the sky was obscured the time was estimated with devices using burning incense.
There are three types of incense buring clocks, Jo-ko-ban, Sen-ko-tokei and Ji-ko-ban.
With the Jo-ko-ban (Jo - Constant, Ko - Incense, Ban - Tray) incense powder was put on levelled ash in a zig-zag or comparable design. Time indicators (such as with the present clock) were placed along the zig-zag. The drawers of the Jo-ko-ban are used for these indicators, for the template which is used to create the incense design, and for the implements used to prepare the ash.