She is speaking, after all this time. It’s a short letter, responding to a commission, promising to supply examples in a month. She thanks the sender for his generous gift of chestnuts. It is so ordinary, so personal. I can feel her shadowy figure gaining substance.

The other letter is longer. Most of it is instructions for making red pigment. “That was her job,” says Kubota-san, surprising me with his English. Oi ground the pigment, producing deep, rich colours for her father, and ultimately for her own work. She has added little drawings.

“. . . knead the shoenji between your fingers, causing all the red powder to fall. Then you boil it down. If you’ve done like so [illustration of fingers kneading] and ended up with this much (shoenji powder) [illustration of quarter-circle] you should put water in a dish like this [illustration of water in dish] and heat it over a fire. Add (the shoenji powder) to the water and boil the water away until the white at the bottom of the dish shows through.”

There is a small hole in the paper: Kubota-san thinks perhaps the recipient burned it while following the instructions. Or perhaps Oi dropped a spark from her tobacco pipe, which she was rarely without.

3:15: We are having tea in a private room in a home behind the miso factory. Hirofumi Koyama’s prominent family has owned Kokuhei-Miso since 1784. We bow and kneel. He serves us chestnut sweets that look like a mountain with streams running down its sides. He found the letter from Oi in this house. It seems obvious that the recipient was his ancestor Iwajiro. Iwajiro was the second son; since his older brother had taken over the miso business, he was free to take art lessons by correspondence.

Koyama-san tells me that twenty years ago he became curious about his ancestor’s painting and looked through storage. Iwajiro left no finished work; his older brother died, and he had to take over the business. But Koyama-san found other treasures — first, a screen with a painting glued on it.

“Oi did this one.”

It is simple, a painting of lilies. Given that there are only five works in existence signed and proven to be by Oi, it is amazing to see. So small, so intimate, so beautiful.

He found more.

“This is very important,” murmurs Kubota-san.