Miru Tights: Cosplay Satsuei Tights | Episode 1
13th episode included in the BD release.
Yua is asked to model an illustrator's designs as a costume for a photo collection the illustrator is producing. Concerned for Yua, Ren offers to accompany Yua to the photoshoot, and Homi somehow ends up rehearsing the photoshoot with Ren and Yua as models.
(Source: Anime News Network)