Regalia: The Three Sacred Stars

Twelve years ago, in the country of Rimgarde, a big incident left an unsolved mystery that has begun to fade from people's memories. Time passes, and sisters Yui and Rena are living peacefully in the Enastoria Empire. However, one day, a large robot attacks Enastoria. This day marks the turning point when the two girls get caught in the vortex of fate.