I Thought Eternal Meant 'Forever'

Seventeen years have passed since Yuna and her guardians defeated Sin and fifteen since the events involving Vegnagun. She now lives quietly in Besaid with Tidus and their children Alesia and Caius. All of Spira thought Yuna's Calm would last forever, but now villages are reporting sightings of Sin. Somehow the Calm was broken and Spira is once again forced to live in fear of Sin.