Shiromuku is an outfit. Source: Able Sisters. It costs 4,800 Bells and sells for 1,200 Bells. Styles: Elegant and Simple; label themes: formal and party. Only available during Wedding Season (Nook Shopping). Added in version 1.10.
Where to get it
Able Sisters: Mabel and Sable's tailor shop on your island, with a fresh rack of clothing on show each day.