Ren Ishida is nearly finished with graduate school when he receives news of his sister, Keiko`s, sudden death. She was viciously stabbed one rainy night on her way home, & there are no leads. Ren heads to Akakawa to conclude his sister`s affairs, still failing to understand why she chose to abandon the family & Tokyo for this desolate town years ago. As he comes to know the figures in Akakawa, from the enigmatic politician to his fellow teachers & a rebellious, alluring student named Rio, Ren delves into his shared childhood with Keiko & what followed, trying to piece together what happened the night of her death. Haunted in his dreams by a young girl who is desperately trying to tell him something, Ren struggles to find solace in the void his sister has left behind.