tabard
An official garment of a herald, emblazoned with a coat of arms or a symbol denoting membership. It is a sleeveless or short-sleeved coat/cloth worn over clothing or armor, either down the front or on the front and back. It is a purely cosmetic item intended to add individuality to someone's look, whereas a surcoat is designed to provide protection from the elements.
Mainly associated with Yakumo Ran, Yakumo Yukari's Imperishable Night outfit, and Ibaraki Kasen.