A liquid ejection system includes a liquid ejection head configured to ejecting liquid, a liquid storage container that includes a liquid storage portion capable of storing the liquid that is to be supplied to the liquid ejection head, and a ventilation unit that constitutes at least a portion of an air introduction portion that is in communication with the liquid storage portion and is configured to introducing air into the liquid storage portion, and is detachable from the liquid storage container. The ventilation unit includes an introduction passage that constitutes at least a portion of a path of air flowing toward the liquid storage portion in the air introduction portion, and an air chamber that constitutes at least a portion of the introduction passage. The ventilation unit is arranged in the periphery of the liquid storage container.