Moonlit Black Cats

Black Cats of the Full Moon (月夜の黒猫団) was a mid-level guild in «Sword Art Online».

Background
The guild was formed with members of a school computer club. Kirito was later recruited by them in-game.

Black Cats of the Full Moon as stated, was a mid-level guild with relatively few members, although all of them barring Kirito knew each other offline. They had hopes for being strong enough to catch up and join the Clearers on the front lines, and with Kirito joining them, believed they stood a chance of catching up.

Except for Keita, who was out bargaining for a new guild home, and Kirito, who somehow survived, everyone in the guild died on June 22nd, 2023 when they accidentally triggered a trap in an Anti-Crystal Area, inside the Labyrinth of the 27th Floor, filled with continously re-spawning monsters higher than their level. After Keita learned of the demise of his fellow guild mates, he committed suicide by jumping off the edge of an Aincrad floor.

Under the belief that he killed the members of the guild, Kirito refused to join other guilds for a year until he was forced into Knights of the Blood after losing a duel against Heathcliff.