That would be a samurai of lost love, namely bespectacled iron foundry manager Nakamura (the deeply sympathetic Masato Sakai), whose world falls apart after his wife is killed on the way home by a hit-and-run driver. He mourns by repeatedly listening to her final answering machine message, in which she gently admonished him for eating prepackaged pots of custard - a habit that now takes on a ritualistic aspect. After serving five years in prison, the boorish culprit Kijima (Takayuki Yamada, one of Takashi Miike's 13 Assassins) is free to resume his wannabe gangster idiocy - until anonymous letters start arriving daily, vowing to end his life on the anniversary of the crime. The writer's identity seems obvious, but is the previously mild-mannered widower capable of such vengeance?

The nominal revenge plotline isn't really the point of this unassuming picture, adapted from his own play by theatre director Masaaki Akahori. Instead it charms through offbeat humour and relatable performances, foregrounding a young ensemble who communicate the vagaries of friendship, grief and karaoke in a lonely world. Plus when it finally arrives, the rain-lashed portentous showdown becomes a small marvel of muddy loser derring-do.