Onso is a Japanese audio cable brand launched in 2009 by HISAGO DENZAI CO., LTD. The line was developed for portable and desktop audio enthusiasts, leveraging the parent company's experience with conductor materials and cable geometry. All Onso products are designed and manufactured in Japan.

The range is built primarily around replacement and upgrade cables for personal audio: MMCX and CIEM 2-pin earphone cables, headphone cables in unbalanced and balanced terminations (3.5mm, 2.5mm TRRS, 4.4mm Pentaconn, 6.3mm), and a smaller selection of coaxial, optical, USB, XLR and speaker cables. Connector and conductor combinations are tuned per series, and product codes such as iect_01, iect_08, and hpct_03 distinguish the different cable families.

Onso occupies a niche in the head-fi and IEM community rather than the broader pro-audio market, often discussed alongside other Japanese cable makers like Orb on enthusiast forums. Pricing spans entry-level replacements to higher-end balanced cables, with the brand's reputation centered on Japanese build quality and a wide matrix of connector terminations for portable players, dongle DACs, and headphone amplifiers.

Onso has 3 products cataloged on Equipboard, including Sheet Music Folders, Instrument Cables, and Headphones & In-Ear Monitors.