In ancient Japan, each month had a poetic name rooted in nature, culture, and seasonal rhythms.
September was called Nagatsuki (ながつき).
You can find this name on traditional Japanese calendars.
Meaning of Nagatsuki (ながつき / 長月)
The name breaks down as:
長 (naga) – “long”
月 (tsuki) – “month” or “moon”
Together, Nagatsuki is often interpreted as “The Month of Long Nights.” As autumn deepens, the days grow shorter, and the nights stretch out — a quiet shift toward the end of the year.
Why “long nights”?
During this time in the Japanese lunar calendar, people began to notice the evenings arriving earlier and lasting longer.
The sky fills with stars earlier, and the air becomes cooler — setting the mood for cozy gatherings, harvest festivals, and reflection under the autumn sky.