HAO is a Japanese boutique effects pedal maker known for a small lineup of handbuilt overdrive, distortion, and boost pedals aimed primarily at guitar and bass players. The brand built its reputation domestically in Japan before gaining a following overseas through boutique dealers, with its output characterized by simple control sets, robust enclosures, and hand-selected components rather than elaborate feature sets.

The HAO catalog centers on a tight family of drive pedals. The Rumble Mod (RM-1) is a Dumble-flavored overdrive with a Boost/Drive mini-switch and a Color control that spans fat, silky tones to edgier, sizzling overdrive. The Rust Driver (RD-1) leans toward Plexi-style crunch, while the Rust Booster offers a clean volume lift, and the Sole Pressure (SP-1) functions as a fat boost/drive. The Rust Ride (RR-1) extends the same design philosophy to bass.

HAO pedals are typically sold through boutique retailers and secondhand markets such as Reverb, and many units are released in relatively small runs. Because of that limited distribution — and a minimal online presence outside Japan — the pedals have become sought-after among players looking for transparent, amp-like drive tones in the same territory as other Japanese boutique builders.

HAO has 7 products cataloged on Equipboard, including Overdrive Effects Pedals, Bass Effects Pedals, and Switch Effects Pedals. Their gear is featured by 4 artists, with the strongest followings in Rock, Pop, and R&B. Notable users include Chiaki Sato, Kazuki Washiyama, and Yusuke (Lynch).