In April 2017, Mitsubishi Heavy Industries Ltd. issued a call for proposals for the redevelopment of the former Saiwaimachi Factory site at the Nagasaki Shipyard & Machinery Works.

[2] As part of the proposal, they sought concepts aimed at enhancing Nagasaki, by creating new lifestyles and job opportunities in the city while bringing their three pillars of "living, working, and leisure" to life.

[7] Their proposal was to build the world's first urban development centred around a stadium, with the overall concept of "the joy of living in Nagasaki".

[8] In November 2018, a real estate purchase was signed, and the land was officially acquired by Japanet Holdings.

It is rectangular in shape and consists of a reinforced concrete structure with a steel roof and stands six floors tall, reaching a height of approximately 28 meters.

[26][27] There are large amount of retailers on the site for shopping, eating and drinking, relaxation and working.

There is also the 'Player's Suite' hospitality package, which consists of 124 premium seats and is as close as you can get to the players and the pitch on a matchday.

[30][31] On 19 December 2022, Japanet Holdings announced they would be partnering with telecommunications agency SoftBank who would provide the ICT for the Nagasaki Stadium City site.