10th calendar sign
癸 is the tenth of the traditional sexagenary cycle signs, used in East Asian calendars and divination. Its standalone meaning is limited to this calendrical role.
The origin of 癸 is uncertain. It is an ancient cyclical character whose pictographic or component history is not clearly established.
The top 癶 looks like a pair of legs stepping forward, and the bottom 天 suggests heaven or a great person. Picture the tenth sign stepping into the celestial order of the calendar cycle.
For キ, imagine a key (キー) unlocking the tenth position in the cycle: key -> キ, and the tenth sign clicks into place.
10th in rank; tenth sign of the Chinese calendar
Water Ox (50th term of the sexagenary cycle, e.g. 1913, 1973, 2033)
Water Boar (60th term of the sexagenary cycle, e.g. 1923, 1983, 2043)
Water Rabbit (40th term of the sexagenary cycle, e.g. 1963, 2023, 2083)
Water Snake (30th term of the sexagenary cycle, e.g. 1953, 2013, 2073)
Water Sheep (20th term of the sexagenary cycle, e.g. 1943, 2003, 2063)
Water Rooster (10th term of the sexagenary cycle, e.g. 1933, 1993, 2053)