Short answers, pulled from the story.
The first handheld role-playing game released by Square in 1989 was The Final Fantasy Legend, known in Japan as Makai Toushi Sa·Ga. This title introduced the SaGa series and featured the first battery save feature on a handheld console.
Game designer Akitoshi Kawazu and his colleague Koichi Ishii designed the original SaGa game. Kawazu intentionally created a difficult experience that contrasted with the Final Fantasy series to establish a legacy of uncompromising gameplay.
The original Romancing SaGa allowed players to choose from eight different characters. Each character had unique storylines that started in different locations and led to vastly different outcomes.
Nobuo Uematsu composed the music for The Final Fantasy Legend while Kenji Ito contributed to several entries. Masashi Hamauzu crafted the music for SaGa Frontier 2 and Unlimited Saga.
By 2019, the SaGa series had sold over 10 million units. Many games in Japan sold over 1 million copies despite the series remaining a cult favorite in the West.