This is an all-in-one I purchased from IENA last year☆ I've only worn it a few times, so it's in beautiful condition! It has a collar, and the fabric is sturdy and looks neat, so you can wear it in a mature style. There's a string on the inside of the waist, so you can adjust it(^^) You can wear it all year round by pairing it with a turtleneck in winter and a sleeveless top in summer(^^) The color is black! I'm 156cm tall and wearing a size M.