As previously announced, Natsume Atari is developing the Eiyuden Chronicles: Hundred Heroes side game, and the scenario is led by Tadashi Satomi, who wrote the scenario and more for Persona and Persona 2.
Here is an overview of the game, via its Steam page:
Eiyuden Chronicle: Rising is a town-building action RPG set in the same world as Eiyuden Chronicle. It weaves together the pre-war tales of various characters who will eventually become your companions in the Eiyuden Chronicle.
The game will introduce a portion of Eiyuden Chronicle‘s cast of characters in an original story with thrilling action and engaging town-building elements.
There might even be some small perks for players that link the game with Eiyuden Chronicles: Hundred Heroes.
Eiyuden Chronicle: Rising is due out for PlayStation 5, Xbox Series, PlayStation 4, Xbox One, and PC via Steam and Epic Games Store in 2022, followed by the main game Eiyuden Chronicle: Hundred Heroes in 2023.
Watch the footage below (from 47:56 to 49:44).