Shunji Iwai’s “Swallowtail Butterfly” has always resisted easy categorization. It’s part fable, part crime saga, part concert film built around a fictional band. Thirty years on, the film also reads like an elegy for a lost era.

In Iwai’s dystopian world, where the yen is the dominant global currency, Tokyo has been nicknamed “Yentown” by the wave of migrants who have come to Japan seeking their fortunes. Underneath the film’s invented pidgin language and junkyard aesthetic is a story about statelessness, belonging and the dignity of those who live on society’s margins.

Ahead of the theatrical release of a new 4K restoration, which Iwai supervised himself, the director sat down with The Japan Times to talk about the technical and emotional stakes of returning to the project and how a story about an imaginary age of yen supremacy feels different today.