To make these costumes available to be bought at the Night Shop, meet these requirements : Note: All costumes must be purchased separately for Mio and Mayu.
Here's how to unlock the 6 different endings. Note: Scenes in Chapter 8 are triggered while traveling with Mayu in the Storehouse, Whisper Bridge, Kiryu Projector Room, and Kiryu-Tachibana Heaven Walkway.
To make these accessories available to be bought at the Night Shop, meet these requirements.