It is sold at the post offices in Kagoshima prefecture only. The area is narrow and the sales amount is little, so it is hard to get. It is a sticker stamp, so it don't need any paste and is very convenient.
The Myoen temple visit is one of the Kagoshima big three event. It is a rare event held by night. Kagoshima people recall Duke Shimadzu Yoshihiro's hardship at the Battle of Sekigahara and they walk back and forth more than 40km between Kagosima city and the Tokushige shrine at Ijyuin town in Hioki city claded themselves in more than 20kg-25kg armor on 14th September according to the old calendar when it is the day before the Battle of Sekigahara. And the next day they must go to thier office as if nothing have happened. It is a very severe event. Only the family of the samurai class took part in the Edo Era in order to discipline patience and staying power that was said Satsuma samurai ware lack in. Ordinary people also take part after the Meiji Era. Now it is held on the 4th Sunday October.
By the way, the Myoen temple is the Shimadzu's family temple, but it was lost by the anti-Buddhist movement in the beginning of Meiji Era once. Because the Tokushige shrine was built at the vacant lot where the Myoen temple used to be, now the goal is at the shrine even the temple is rebuilt on the west side of the shrine. As a result, people mistake the shrine and the temple. The taxi driver sometimes bring the visitor for the temple to the shrine. It is too hardly distinguishable. So the Myoen temple ask Hioki city which is the sponsor of the event to change the event name to the Yoshihiro festival or the Tokushige shrine worship and tell the shrine from the temple.
It is up to people to visit the Myoen temple, worship the Tokushige shrine or go both.
