Gai Tsutsugami is a character and is one of the main characters of Guilty Crown. He's the mysterious and charasmatic leader of the military resistance organization known as Funeral Parlor and fights for the freedom and liberty of Japan and the Japanese People from the oppressive GHQ Puppet-Regime. While he appears as a protagonist for the first half of the show, he's later revived and defects to GHQ and Da'ath and ultimatly becomes one of the main antagonists for the second half of the series.
Gai is the seventeen-year-old rebel leader of Funeral Parlor, Gai is described as Shu's rival and seeks to use Shu's "Power of Kings" to fight against the GHQ. His Void is a gun that can unlock people's Voids.
Gai is an excellent strategist; every one of his moves appears to be planned down to the ninth decimal point. He is able to see people's Voids, and thus the shape of their souls. Likewise, Gai can reformulate his plans and factor in new obstacles at a moment's notice.