Aim: The complex genome of a Japanese radish (Raphanus sativus) cultivar named ‘Okute-Sakurajima’ with an extremely large edible round root was analysed to explore its genomic characteristics. Methods and Results: Single-molecule real-time technology was used to obtain long sequence reads to cover 60 of the genome. De novo assembly generated 504.5Mb contigs consisting of 1,437 sequences with the N50 value of 1.2Mb and included 94.1% of the core eukaryotic genes. Nine pseudomolecules, comprising 69.3% of the assembled contigs, were generated along with a high-density SNP genetic map. The sequence data thus established revealed the presence of structural variations and rearrangements in the Brassicaceae genomes. Conclusion and perspective: A total of 89,915 genes were identified in the ‘Okute-Sakurajima’ genome, 30,033 of which were newly found in this study. The genome information reported here will not only contribute to the establishment of a new resource for the radish genomics but also provide insights into the molecular mechanisms underlying formation of the giant root.