"The Siwnin Sails" is a solo album consisting of eight songs written and composed by Shoko Numao, an emerging Japanese singer-songwriter. Numao studied vocal and composition focusing on jazz at Dublin City University in Dublin, Ireland, where she trained to use her voice as an instrument, exploring the expressive possibilities of the voice and laying the foundation for her current approach. Since returning to Japan in 2021, she has been based in Tokyo, performing her own songs, both in collaborations with various musicians and as a solo artist. She has captivated live audiences with her poetic and introspective songs as well as her translucent voice, which occasionally reveals a flickering, ethereal quality.

'The Siwnin Sails' features eight songs written and composed between 2016 and 2024, all performed by Numao herself on guitar and vocals. All eight tracks were recorded in July 2025 at Muriwui in Tokyo. This album follows her first album, 'Live at Ftarri — Lena', released in 2023 on the ftarri label, but it is her debut solo album.