The lunar calendar and the solar calendar count time in different ways. The solar calendar is based on the movement of the sun and has fixed dates, starting on January 1 each year, while the lunar calendar is based on the cycles of the moon, so its months begin with each new moon.
Because of this, the start of the lunar year changes every year when compared to the solar calendar. It usually begins sometime between late January and mid-February.
The solar calendar is the system we use in everyday life, commonly known as the Gregorian calendar.
Setsubun-sai 節分祭
It marks the transition into spring (the day before Risshun).
Kinen-sai 祈年祭 & Haru-matsuri 春祭
It is the eve matsuri for Hatsuuma-sai, where we celebrate spring’s arrival and the beginning of the new season.
Hatsuuma-sai 初午祭
Celebrated on the first Horse day (午の日) of the second lunar month.
Many Omatsuri and ceremonies were originally celebrated according to the lunar calendar. However, when Japan adopted the solar calendar in 1873, many of these dates were shifted to fixed dates.
For example: Hina-matsuri 雛祭り, Kodomo no hi 子供の日, Tanabata 七夕, and Tsukimi 月見
As you may know, there are 12 zodiac signs, known in Japanese as 十二支 (jūnishi), which are:
Rat 子（ね）・Ox 丑（うし）・Tiger 寅（とら）・Rabbit 卯（う）・Dragon 辰（たつ）・Snake 巳（み）・Horse 午（うま）・Sheep 未（ひつじ）・Monkey 申（さる）・Chicken 酉（とり）・Dog 戌（いぬ）・Wild Boar 亥（いのしし）
After the lunar year begins, the zodiac cycle continues day by day in a repeating 12-day sequence.
For example, Hatsuuma-sai is celebrated on the first Horse day of the second month in the lunar calendar. To determine this date, we begin by identifying the second new moon, which marks the start of the second lunar month. Next, we determine which zodiac day it corresponds to. From there, we simply follow the cycle forward until we reach the first Horse day within that month.
