旬

Hint: Here's info from Wikipedia regarding why this kanji exists, which helped me remember it: [Japan also divides the month roughly into three 10-day periods. Each is called a jun (旬). The first is jōjun (上旬); the second, chūjun (中旬); the last, gejun (下旬). These are frequently used to indicate approximate times, for example, "the temperatures are typical of the jōjun of April"; "a vote on a bill is expected during the gejun of this month."].

Source: Kanji Koohii community