Shimonoseki City Aquarium Kaio-kan is a distinctive maritime facility completed in 2000, located at Arupkaport in Shimonoseki, Yamaguchi Prefecture. Designed by Nippon Design Kyushu Branch, this innovative structure seamlessly integrates aquarium and botanical garden functions within its architectural framework. The building exemplifies early 2000s Japanese design philosophy, featuring a contemporary aesthetic that reflects its waterfront location. Its spatial organization effectively combines educational and recreational purposes while maintaining architectural coherence. The facility demonstrates thoughtful integration of natural and built environments, making it a notable example of specialized institutional architecture that balances form, function, and environmental context.