The Night Sky Sword, often called "The Black One", is a long sword that is Kirito's personal one-handed sword in Underworld. It features a 3.5mm thick carbon steel blade with a two tone black and silver finish. All black in colour with two small emblems on the cross guard, cast alloy hilt and a lacquered wooden sheath.

Overall length - 102.5 cms
Blade length - 77 cms
Handle length - 21 cms