Beyond Fate

Soft-missable. Enya and Su's story starts with "Looking at You" the moment you first reach Xion (The Last Gulp, western Xion). The finale needs D1G-g2r's "CnL - Communicate and Link" step done first (see Beep!) and access to the Great Desert. All of it dies once you advance past Xion after Abyss Levoire, so wrap it up in that window - otherwise you're redoing it in NG+.