The reason soba was chosen as the film's central dish was based on the location the film was shot at. Oishida, Yamagata Prefecture is famous for its soba culture. As shown in the film, the ‘restaurant’ is really a tatami room in someone’s house. It was apparently a custom for wives in the town to make soba to entertain visitors, and if they were particularly good at it, they would start serving the noodles and earning a living from it. That’s how the [home-restaurant] culture developed. The second reason was because of soba’s metaphorical qualities - it's something that is simple but goes very deep (as it takes a lot of time and technique to master).