This year 2018’s OTSUKIMI is September 24 and October 21.
In Japan, it is said that only once moon viewing a year is called 片見月【KATAMI-TSUKI】;”one side viewing moon” and it is not good fortune.
So,Japanese tradition is watching the moon twice. Second time O-TSUKIMI is about one month later of the first and it is called 後の月見【NOCHI NO TSUKIMI】：“Late moon viewing”.
Usually,people watch 十五夜【JYUUGO-YA】 “fifteenth night” full-moon at O-TSUKIMI while in Late moon viewing people 十三夜【JYUUSAN-YA】”thirteenth night” moon view.
十五夜【JYUUGO-YA】is Full moon, but 十三夜【JYUUSAN-YA】is slightly lucking.
Japan has tradition to love incomplete, not perfect things.
There is a word “things full become lack” and Japanese sometimes dislike things perfect.
Emperor 宇多【ＵＤＡ】 started the habit of thirteen night moon viewing in 平安【 HEIAN】 period about 1200 years ago.
