man-made in japan

it's a truman world.

"Ocean Dome is known as the world's largest indoor water park (300m-100m-38m),
with a retractable roof. The air temperature is always kept around 30º C
and the water temperature is kept at around 28º C.

The name Seagaia is a combination of the words "sea" and "gaia",
which is Greek for earth. It's located near the Pacific Ocean on Kyushu Island.
(thanks to Nana Yoshizumi)."