Oasis 21 is a complex located in the center of Sakae, Nagoya, that combines a park, a bus terminal, and a commercial facility. The most eye-catching feature is the large glass roof "Water Spaceship" that floats 14 meters above the ground. This large roof is filled with water and is fantastically lit up at night, creating a mysterious sight as if the water is floating in the air. From the promenade where you can walk on the water surface, you can see the beautiful night view of Nagoya cityscape and the illuminated Chubu Electric Power MIRAI TOWER (formerly Nagoya TV Tower), and it is also popular as a photogenic photo spot that looks good on social media.

Under the "Water Spaceship" is the event square "Galaxy Square", where various events and concerts are held and it is always bustling. In the basement, there is a commercial facility "Shop & Restaurant" with about 30 stores such as fashion, miscellaneous goods, and restaurants, where you can enjoy shopping and dining.

Various events are also held throughout the year. In the summer, the Oasis 21 Summer Festival is held, featuring illuminations and food stalls, and attracts many visitors.