A hickey, love bite, or slag tag is a bruise or mark caused by the [[kiss|kissing]] or sucking of the skin, usually on the neck or arm. The mark is created by the bursting of superficial small blood vessels under the skin.

It's sometimes called a "kiss mark", but this should not be confused with the [[lipstick mark]] tag. Also, apparently both lipstick marks and hickeys are tagged as キスマーク on Pixiv.
キスマーク 키스마크