The Japanese television format that inspired the UK version of Dragon's Den was Money Tigers.
Money Tigers was a Japanese business reality programme in which entrepreneurs presented proposals to wealthy investors. Its format supplied the central idea later adapted for several national versions: business owners pitch for investment, investors question them and the entrepreneur may negotiate over valuation and equity.
The UK adaptation was produced for the BBC and first aired in 2005. British producers retained the core pitch-and-investment structure but used the name Dragon's Den, turning the investors into “Dragons” and giving the programme its distinctive British identity.
The format is often confused with Shark Tank because both shows feature entrepreneurs seeking capital from a panel of wealthy investors. Shark Tank is the American adaptation of the same broad format family, whereas Money Tigers is the Japanese programme generally identified as the original inspiration for Dragon's Den.