decameron, 10-day period, season (for specific products)
JLPT1 G7 S6 F1162
An abbreviated form# of 匀 (arrange in a circle) + 日 sun/day → one *cycle of ten days* (according to a traditional calendar). *The season when foods taste their best* is by extension from the minor meaning of "pervade" (← time when fish, fruits and vegetables are to be found all over/at their peak).
[Full Kanji Etymology List]