Coat of Midnight (コート・オブ・ミッドナイト, Kōto Obu Middonaito?) is Kirito's first generation leather coat, the last being the Blackwyrm Coat.
Chronology
Aincrad Arc
Aria in the Starless Night
Bonus Item: Coat of Midnight.
Kirito acquires this coat as a bonus drop by landing a Last Attack hit on the 1st Floor boss. After the defeat of the boss, some of the raid party's members bring up the issue of the Beta Testers having exclusive information about the boss, which led to the death of the raid party's leader, Diabel. Fearing that the discrimination of Beta Testers would never end, Kirito proclaims that only a small number of Beta Testers actually had more experience and information than regular players and dubs this small group of players as Beaters to separate himself and others like him from all other Beta Testers. He then takes out the coat in front of the raid party to show off his status as a Beater, thus taking all the hatred towards Beta Testers onto himself.
After this theatrical performance, he only uses the coat when he's outside the city, as he takes it off before going into town to hide his identity, since he has become Sword Art Online's most despised player.