It costs 10 million yen to rethatch the roof. They do it once every 30 years. The thatch is Japanese pampas grass (susuki) from the base of Mt. Fuji.

The rethatch cost is subsidized by the national government and municipality. So the family only pays one-third the cost of 10 million yen. In the old days, they had family and friends gather the thatch and the roof was rethatched by the villagers as a community project. Not anymore. They have to hire professionals to do it which cost a lot of money.