The Mathematics of Kisetsu.

I've always believed a year is not twelve months.

It is 72 distinct moments — each one precisely named by people who were paying closer attention than we are. Skylarks sing. First peach blossoms. Rotting grass becomes fireflies. Observations so specific they could only belong to a single week in a single season. Blink and the moment has passed into the next one.

I built Kisetsu inside this calendar.

Four times a year I choose one micro-season — one kō — and I find the form that carries it. Five forms. 72 pieces of each. 360 total.

The degrees in a circle. The geometry of a year completing itself. I didn't plan that. I noticed it, and then I couldn't unnotice it.

Each of the 72 pieces exists once for every micro-season the calendar has ever named. Not more. The number was never a decision — it was already there, waiting in the math.

When the last piece of a drop ships, that kō is retired. It does not return the following year. It does not return ever. Across 18 years and 72 drops, every micro-season will have lived once in ceramic form — and then the circle closes.

I don't know what happens after that.

For now there is just this — one moment chosen, made into something you can hold, and then released.

Ki-set-su. Season.