MOS Burger opened in Japan in 1972. Originally the company was a spinoff of founder Atsushi Sakurada's previous company, Merchandising Organizing System. Later, the company began to use playful English phrases in marketing materials to explain the name, settling on the backronym "Mountain Ocean Sun". The restaurant introduced the Tsukune Rice Burger in 1987, using a bun made of rice. The first Singapore branch opened in 1993 at Isetan Scotts.