MESS are strange cube-like aliens that appeared in the first part of Gatchaman Crowds. While thought to be malevolent enemies because of their actions, it was only until Hajime revealed their true means of communication that they became allies.
MESS are composed of several small multi-colored blocks that form a cube. They also featured a strange mass that contained all of the people and objects they had collected. As found by Hajime, they communicate through movement and touch.
MESS are able to take a human appearance that is noticed only by those with NOTEs. They are able to contain humans in their own bodies in the fom of a dark yellow mass that can only be extracted after they are slain or if they will it to be. MESS are also able to change their size or travel in groups.
For an unstated reason, MESS appeared on Earth a few years before the start of the series and began capturing humans until they were stopped by the G-Crew. This continued until the new recruit Hajime Ichinose discovered their true nature and by communicating with a MESS freed the captured humans. Afterwards, MESS became friends with the G-Crew and even helped in the crisis created by Berg Katse.