The original Japanese television programme that inspired the British series Dragons' Den was Money Tigers.
Money Tigers was a Japanese business reality programme in which entrepreneurs sought financial backing from successful businesspeople. The format was later developed and licensed internationally, producing local versions with different presenters, investors and business cultures.
The British adaptation retained the basic pitch-room structure. Entrepreneurs describe their products or companies, state how much money they want and offer a share of the business. The investors then question the proposal and decide whether to make an offer.
Shark Tank is a related American adaptation of the same broad format, not the Japanese programme that directly inspired the British title. The distinction is useful because “sharks” and “dragons” are different regional names for comparable investor roles.