Vest
Depending on how you wear them, vests can give a character a whole new look. Anime characters usually wear two main types of clothes: a formal three-piece suit that makes them look sharp and smart, or a school uniform sweater vest that makes them look friendly and approachable. It is a layer that makes an outfit look more interesting without adding the bulk of a full jacket. It often draws attention to the character's torso and posture.
A well-fitted waistcoat on a butler or bartender character looks very professional and elegant. You can often see them fixing their tie or cuffs, which is a great pose for fan art. On the other hand, there are the rebellious characters who wear them unbuttoned over a t-shirt, or the fantasy adventurers who wear leather vests with a million pockets for their gear. It makes a nice shape that narrows at the waist, making men look broad-shouldered and women look stylishly tomboyish or proper.
Vests add a level of detail that makes a design feel complete, whether it is a knitted layer for a high school setting or a silk brocade piece for a gothic aristocrat. They are great for fans who like tailored clothes and the look of a "gentleman" or "student council president."