|This article is about a location in Ciconia no Naku Koro ni.|
The Glass Sea was created in World War III when a solar warhead was launched at Japan. Everything and everyone within a 100 kilometer radius, from central Gifu to Osaka, evaporated and vitrified. The resulting crater split Japan into two territories, AOU Japan and COU Japan, and they have since recognized the Glass Sea as a World War Relic and maintain its status as neutral territory.
After a spirit field containing Rare Spiritium was discovered to be under the Glass Sea, tensions between AOU Japan and COU Japan began rising.
- Phase 1, Chapter 3: It's a Wrap Public Bath.