Ryujinko Onsen, a popular hot spring village surrounded by lush greenery and water, has a legend of the dragon god that has been handed down since ancient times. Sakuma, who won a lodging ticket in a lottery, intends to visit this place as his first solo trip, but for some reason Azazel comes along. Sakuma hits it off in the open-air bath with Mayu Hanasaki, an office worker who came here on a company trip, and has dinner with her. At the dinner table, she is told by the proprietress of a terrifying legend about Lake Ryujin. And that night, a tragedy struck Ryujinko Onsen...! !