Go-nin Gumi (五人組み) is a group consisting of five people with the aim to improve a product or develop a new product.

This practice in Japan is also known as Quality Circle or Creativity Circle.

The Gonin Gumi was (is?) also a street gang that was active until about 2003 in the Edogawa, Harajuku, and Setagaya areas of Tokyo. Name was taken from the term above, but the products and methods this case that were improved and developed were streetfighting, petty theivery, covert methods of killing,drug smuggling, etc. While the Gonin gumi disappeared, their name is still quite well known in underworld circles as an extremely brutal and ruthless street gang.