S101 was a budget-oriented guitar brand sold by America Sejung Corporation, the U.S. distribution arm of South Korean conglomerate Sejung, headquartered in Ontario, California. Instruments were manufactured at Qingdao Sejung Musical Instrument Co., Sejung's 700,000-square-foot piano and guitar factory in Qingdao, China, which was built in 2001 under chairman Soon Ho Park.

The S101 catalog covered a wide range of entry-level and mid-budget instruments, including dreadnought and other acoustic guitars, Strat- and Les Paul-style electric guitars, semi-hollow electrics, electric and acoustic bass guitars, resonator guitars, banjos, mandolins, and small solid-state guitar amplifiers. The Qingdao factory also produced instruments on an OEM basis for other companies, with reports of Epiphone-branded guitars being built there during the late 2000s.

S101 instruments were distributed in the United States from roughly 2002 through 2013, sold through retailers such as Guitar Center and Musician's Friend alongside the Sejung-distributed Canvas guitar line and the Hobart M. Cable, George Steck, and Falcone piano brands. The guitars are most commonly encountered today on the secondhand market and are generally regarded as inexpensive beginner-tier instruments rather than professional-grade gear.

S101 has 4 products cataloged on Equipboard, including Solid Body Electric Guitars, Semi-Hollowbody Electric Guitars, and Electric Basses.