noun
first day of the equinoctial week
Refers to the first day of the Buddhist equinoctial period (higan), a time for visiting graves and honoring ancestors. The spring equinox week starts around March 17-18, and the autumn equinox week starts around September 20-21.
今年の春の彼岸の入りは三月十七日です。
This year, the first day of the spring equinoctial week is March 17th.
彼岸の入りにはお墓参りに行く人が多い。
Many people visit graves on the first day of the equinoctial week.
彼岸明け is the last day of the equinoctial week, contrasting with 彼岸の入り which is the first day.
Compound of 彼岸 (higan, 'equinoctial week') + の (possessive particle) + 入り (iri, 'entering'). The term is rooted in Japanese Buddhist tradition.