Aesculus turbinata

About

Aesculus turbinata, common name Japanese horse-chestnut, is native to Japan but cultivated elsewhere. It is a tree up to 30 metres tall. Flowers are white to pale yellowish with red spots. Capsules are dark brown, obovoid to pyriform. The seeds were traditionally eaten, after leaching, by the Jōmon people of Japan over about four millennia, until 300 AD. Today the seeds are used in Japanese cuisine to prepare tochimochi.

Summary from Wikipedia