The Hanamaki Souminsai is held every year on January 2nd at the Koshio shrine on Mount Koshio.
It's a purification festival for the new year, it starts by making mochi (rice cake) and getting blessings from the local Shinto priest. After that, the participants walk up the mountain holding a torch and a blessing in their mouth to give them more determination.
Hanamaki Souminsai in video
The event finishes with the participants fighting over a pouch, a good luck bag. The fight can last over an hour and is extremely fierce, many participants end up badly bruised up. The winner is said to have a prosperous year.