Amagi Development (甘城企画 Amagi Kikaku?) is the company which will take over the running of Amagi Brilliant Park if it doesn't get 500,000 visitors by the end of three months. According to the manga, Amagi Developement is a business investor that happens to be a large shareholder of the park. In 1982, a contract was signed which stated that the administration of of Amagi Brilliant Park would be handed over to Amagi Development. Once they have obtained the administration rights of the park, they plan to shut down it down.
Takaya Kurisu is employed there and apparently holds a high position within the company.
Seiya Kanie is almost scouted to work there.