Summon Night: Twin Age - Don't Look Back 

The dungeon theme for Mt. Eurinoch, one of the two you can pick from depending on which party member's suggestion you go with during the almost-midpoint of the game.
Music's composed by Kengo Sakurai. Summon Night as a property is owned by Bandai Namco, although this game was published by Atlus in North America and Banpresto in Japan.