Sai Yukitsugu

Sai Yukitsugu (狭井 雪嗣), known as Itsuki (イツキ) in Gun Gale Online (GGO), is an original Sword Art Online game character and one of the main characters in Sword Art Online: Fatal Bullet. He is one of the most famous and top skilled players in Gun Gale Online and is the leader of the Squadron "Alphard". While he is seemingly a calm and carefree player, Itsuki is secretly on a constant search for something to excite him. This obsession leads to him becoming the main antagonist of Fatal Bullet.

Gun Gale Online
Itsuki has a red- and narrow-eyed avatar with dark grey hair. His outfit prominently features black and white colours, with red seams overall. The inside of the arms of his long-tailed coat are light blue. He carries gun shells on the side and back of his coat. His canon choice of weaponry is a Dragonfall that resembles a real life Dragunov Sniper Rifle as his primary and a Sirius Optical Sub-Machine Gun as his secondary.

Personality
Itsuki is a mysterious character who is never willing to share anything regarding his real personality. Instead of being an open character, he enjoys providing various bits of information about himself, before promptly following up by claiming that he was joking, thus even his Squadron members do not know much about him. Aside from this, he is a skilled leader and a genius player when it comes to laying decoys and traps in GGO.

Towards the end of Fatal Bullet, Itsuki opened up to the Protagonist for the first time, confessing to the boredom he feels, as well as revealing that the only thing in the world that had sparked his heart was them. In the final chapter of the game, he admitted that he had desperately longed for the Protagonist's utmost friendship, to the extent that he did not care for anything that could pose a threat to that, going as far as creating a devious plan that could kill himself, the Protagonist, Kureha, and Zeliska.

Fatal Bullet
While on his way to enter a tournament implemented as part of a special update to GGO, Itsuki noticed Kureha and the Protagonist also registering for the event. Having heard of Kureha's reputation, the man decided to approach the pair to assess their potential, during which he learned the Protagonist had only begun playing GGO that very day. Impressed with the latter's resolve to participate in the tournament despite their inexperience, Itsuki expressed his wish to face them in the competition, before taking his leave.

Shortly after the start of the tournament later that day, Itsuki unexpectedly encountered Kureha and the Protagonist again while navigating the tournament dungeon with his companion Python. Although tempted to fight the duo, he decided it would be too easy to defeat them for the fight to be worthwhile. Instead, he sent them ahead to handle a difficult enemy deeper within the dungeon, promising to not pursue the two {Informal phrasing -Gsi} if they could defeat it. After Kureha and the Protagonist managed to vanquish the monster, Itsuki and Python parted ways with them at a fork in the path not far ahead.

To Itsuki's disappointment, the route he chose was filled with traps that weakened him and decimated all his other companions, which left the man unprepared when he encountered Kirito the Photon Sword Wielder and his partner Asuna. Only surviving the fight with the pair due to the tournament's duration expiring, he was automatically transported to the SBC Glocken, where he was reunited with them alongside Kureha and the Protagonist. To his shock, Itsuki learned the Protagonist had acquired a rare Type-X ArFa-sys unit. Bemoaning his own misfortune, the man nevertheless congratulated the new player on their accomplishment but declined Kirito's invitation to a party to become better acquainted with each other, explaining he needed to meet with his companions from the tournament.