The film imagines a parallel-universe version of Japan which also suffered a nuclear crisis but was less lucky than its real world counterpart. It's a place where fallout readings are a part of the weather forecast and gas masks are as ubiquitous as black suits and Gucci bags.
Three old friends, former members of the same biker gang, get together after many years for one last trip together. Time has passed but their friendship remains the same; and so does the sense of freedom in every mile.