Jin possesses a Quirk that allows him to create copies of himself or others, one at a time. The clones possess the same personality and abilities as the original, with Jin claiming that he can create as many clones as he wants. He was also shown being able to detect when one of his clones was destroyed.
Because Jin's clones share the same personality as the original Jin, they can also rebel against him or each other. When the clone suffers a certain amount of damage, it turns into dark, viscous liquid.