Actually, this game seems to take place a little before the first one in the series, Last Embryo.
I'm still in the early game, but some of the hints I found to that end would be the mention that Zirnitra (the dragon boss you beat near the end of Last Embryo) is still alive in Aletia, as well as the Festival of the Sun (that takes place during the second half of the first game) not having been held yet.
Granted, you discover about Zirnitra in a bookshelf, so the book could just be old. And the Festival of the Sun they mention here could be another one, instead of the exact same one in The Last Embryo. However, the early game here gives no hint at all for the People of Eden and People of Michelin being at war. So at least for now I believe this game takes place a couple days to a couple weeks prior to the first one.
Also: man, having different people translating these games really hurt compreension sometimes. Its one thing to have People of Eden and People of Michelin becoming Edenfolk and Michelinfolk in Ark of Artemis, but it took me a second to process Jirunitra here was Zirnitra from Last Embryo, as well as "Stargazing God" being "The God of Astrology" of the last two games.