Jigai as heaven are put inside down, starting with 12 of them in the center representing 12 months, then 7 shells as the days of the week are added, and finally, exactly 360 clamshells representing the days of a year are arranged in 9 rows.
天にかたどった地貝の伏せ方は、まず中央に12ヶ月にかたどって12個を伏せ、7曜日にかたどってしだいに7個をくわえ、1年の日数にかたどった360個のハマグリ殻を過不足無く9列にならべる。