This is “The King Lost in Time” from the RPG “Etrian Odyssey III: The Drowned City” by ATLUS.
The music is composed by Yuzo Koshiro.
This is a BGM that can be heard in the underwater city called “Deep city”, which you reach after completing the early part of the game.
It’s a calm and serene song.
The serenity is probably impressed by the same note (3f on 2nd string) is played continuously as an accompaniment in bars 1~2nd.
It uses broken chords throughout the piece, which is also peaceful.
The bass in bars 7~8th, I-IM7/VII-vi-I/V (E-EM7/D#-Cm7-E/B), flows down gradually and smoothly.
This is the same progression as the beginning of J.S. Bach’s (original) “Air on the G String”.
The end is IV-IVm-I (A-Am-E), a gentle, popular chord progression.