Ryohin Keikaku Co., Ltd. (株式会社良品計画, Kabushiki-gaisha Ryōhin Keikaku), or Muji (無印良品, Mujirushi Ryōhin) is a Japanese retailer which sells a wide variety of household and consumer goods. Muji's design philosophy is minimalist, and it places an emphasis on recycling, reducing production and packaging waste, and a no-logo or "no-brand" policy. The name Muji is derived from the first part of Mujirushi Ryōhin, translated as No-Brand Quality Goods on Muji's European website.

Muji started with only 40 products in the 1980s. By the end of the 2000s, Muji was selling more than 7,000 different products.

Some of their products include pens, pencils, notebooks, storage units, apparel, kitchen appliances, food items, and household care products. Muji has also created an automobile. Muji storefronts such as the one in New York are large and stocked with nearly every single product available. The primary business also includes Café Muji, Meal Muji, Muji Campsite, florist and home furnishing; the company has also engaged in architectural projects such as Muji House.

Muji is positioned as a "reasonably priced" brand, keeping the retail prices of products "lower than usual" by the materials it selects, streamlining its manufacturing processes, and minimising packaging. In April 2019, Muji opened its largest Muji store in Ginza, Japan. The company added Atelier Muji Ginza located on the sixth floor.

Muji has opened hotels in Shenzhen, Beijing, and Ginza, Tokyo.

Mujirushi (no-brand) Ryōhin (quality goods) began as a product brand of the supermarket chain The Seiyu, Ltd. in December 1980. The Mujirushi Ryōhin product range was developed to offer affordable quality products and were marketed using the slogan "Lower priced for a reason." Products were wrapped in clear cellophane, plain brown paper labels and red writing. Mujirushi Ryōhin's drive to cut retail prices for consumers saw the company cutting waste by, for example, selling U-shaped spaghetti, the left-over part that is cut off to sell straight spaghetti.

In 1981, Seiji Tsutsumi, the president of the Seiyu Ryutsu group proposed opening a dedicated shop for Mujirushi Ryōhin products. Although the idea was rejected by the directors of Seiyu, the advisory board of the company supported the idea, proposing the idea of a shop positioned against mass production. The company began to develop products that would allow the shop to expand from a supermarket product range to an independent product company. Such products included food, clothing, stationery, and household goods.

In 1983, the first directly operated Mujirushi Ryōhin store opened in Aoyama, Tokyo. In 1985, Mujirushi Ryōhin started overseas production and procurement, started to place direct factory orders in 1986, and in 1987 Muji started to develop materials globally. And it was a real success.