Seven years ago, a mysterious monster was found deep in a rural coal mine. Since then, rumors of a plague spread through the small town, and people experience an unexplainable mental illness. A young Shugendo practitioner goes missing only to resurface transformed, intent on exorcising the world from the monsters haunting it.

Arakawa Ao lives happily on his own and hardly ever leaves Shimokitazawa, where he works at a vintage clothing shop, goes to occasional concerts and hangs out at his favorite bar. Then, he gets an unusual request to appear in an independent film.

Kou, who had been living a dull life with no hope for the future, meets the charismatic Hee Bro. and regains the sparkle in his life. When Hee Bro. suddenly dies, Kou tries to find the definition of goodbye.