On the way to Hyakuninohama, there is a small swamp with a circumference of about 400 meters that has a sad legend.
A young Japanese man and an Ainu girl are in love with each other.
Eventually, the day comes for the young man to say goodbye to the Ainu girl after his life in Ezo.
The two mourn their unfulfilled love and vow to meet again in the afterlife.
The tearful girl disappears from the beach, and one day, a swamp appears.
The swamp was made by the tears of the daughter, without anyone's knowledge.