Kikoku is a large version of the typical Japanese sword type known as nodachi. It has an oblong-shaped hilt trimmed with short white fur, a purple grip with two white rings around it and a yellow pommel, sheathed in a black scabbard decorated by white crosses from the opening to the bottom, and with a small piece of red rope tied near its opening. The said rope often varies in length in several forms of media, though it has so far been its longest in One Piece: Pirate Warriors 2 and 3.
Due to its size, Law usually carries Kikoku over his shoulder (in contrast to other sword-wielding characters in the series, who either carry theirs on their hips or over their backs); yet in other times, he delegates one of his crewmates (namely Bepo) to carry it for him.
Law combines Kikoku with his Ope Ope no Mi powers, with the sword serving as a "scalpel" or an "injection needle" of sorts, using it to cut or pierce at a distance. At full power, Law can bisect an entire mountain or meteor. The sword could also block Doflamingo'sstrings, which is a notable feat as all weapons until then were easily cut by the them (unless they were reinforced with Haki).
When Law made his debut, the sword was seen alongside him. He would keep the sword with him at most times, and on occasion let Bepo carry it for him. When Vergo defeated Law and restrained him, the sword was confiscated, but Law used his powers to retrieve it with ease. After Law was brutally defeated by Doflamingo, the latter took the sword along with an unconscious Law. However, the sword eventually returns on his person when Law is rescued by Luffy and Viola.