Rey spring left by Kobo Daishi

In the past, when Kobo Daishi (Kukai) was in trouble in the mountains of Umani on the way to Shikoku Pilgrimage, I was struck by the fact that a poor couple treated me with all their heart. It is said that he left chestnuts that can be harvested seven times a year, and a cold spring that springs out of the ruins of the master's cane.
You can put 100 liters for 100 yen.