Echoed Memories is a direct sequel to Gaia's Melody: Echoed Melodies.
While playing it isn't required, EM2 allows you to input EM1's save data, so you can customize your story further.
The game follows a group of already-heroes, focusing on their personal growth and development, and their interpersonal relationships as they progress through solving the mysteries of the overarching story.
They're searching for who they are, what they want, and what they need to achieve it.
The game deals with heavily emotional themes and topics.