Pretty Pink Ribbon

The Traveling Merchant carries it, which makes this a waiting game rather than a hunt. His stock rerolls on every visit and he packs up at dusk, so check the list each time he shows up and buy the pieces the moment they appear. Skip a day and you are waiting on another arrival for a fresh roll.

Three cosmetic parts for the social slots and nothing more. The leg piece is unusual: Terraria gave the stockings a second sprite so male and female characters wear them differently, which almost no other vanity legwear bothers with. A party in the same outfit will not look quite uniform.

The outfit is Madoka Kaname from Puella Magi Madoka Magica, ribbon included, and the shapes line up closely enough that the nod is not subtle.