The Japanese business programme that inspired the British series Dragon's Den was Money Tigers.
Money Tigers was a Japanese television format in which entrepreneurs presented business proposals to potential investors. Its central idea was exported internationally and adapted for different audiences, with the British version adopting the title Dragon's Den and its investors being known as dragons.
The British adaptation preserved the core negotiation: entrepreneurs request a specific amount of money for a stated percentage of their business, and investors can ask questions before deciding whether to make an offer. Multiple investors may negotiate together, although a televised deal is generally subject to later checks.
A common mix-up is to name Shark Tank, the United States programme that uses a similar format. Shark Tank is an adaptation within the same international franchise family, not the Japanese programme that originated the concept. Money Tigers is also sometimes rendered or described through translated titles, but that is the canonical English title associated with the format's Japanese source.