Gakken is a Japanese publishing company founded in 1946 that has become known in music circles through its Otona no Kagaku ("Science for Adults") magazine series, which packages a buildable instrument or gadget with each issue. The line gained an international following after the release of the SX-150, a small monophonic analog synthesizer played with a stylus along a ribbon-style pitch strip and shaped via cutoff, resonance, attack, decay, and LFO controls. A revised SX-150 MARK II followed, expanding the modulation options and external I/O.

Beyond the SX-150, Gakken's music-oriented kits include a Mini Theremin built around a single antenna, a Mini Electric Guitar, an electric steel drum, and the Toy Record Maker, a desktop lathe that cuts playable 5-inch records from blank discs using audio piped in from a phone or other source. Most kits ship with a companion magazine covering the instrument's history and circuit, and assembly is generally screwdriver-only with no soldering required.

The Otona no Kagaku instruments have a strong DIY and circuit-bending reputation, and modding guides for the SX-150 and theremin circulate widely on hobbyist sites. The kits are typically sold through Japanese bookstores and hobby retailers, and have been imported and resold by electronics shops such as Adafruit and Maker Shed.

Gakken has 5 products cataloged on Equipboard, including Synthesizers, Portable & Arranger Keyboards, and Tabletop Synthesizers. Their gear is featured by 6 artists, with the strongest followings in Electronic, Rock, and Pop. Notable users include Jonny Greenwood, Benny Blanco, and Jamie Stewart.