What makes the Shusui a Kokuto, or black blade, in One Piece lore?

In the One Piece universe, a Kokuto is a blade that has been infused with its wielder’s Haki over countless engagements until the steel itself permanently transforms, turning black and increasing in grade. The Shusui reached this status under Shimotsuki Ryuma, the legendary swordsman of Wano Country, centuries before Zoro acquired it. Only two confirmed Kokuto exist in the story — the Shusui and Yoru, Dracule Mihawk’s great sword. This makes the Shusui exceptionally rare within the lore and a highly sought-after replica among collectors. Our reproductions honor that narrative significance with a darkened blade finish and flame-pattern hamon that visually distinguish it from standard polished katana replicas.

Is the blade sharpened, and how should I handle it safely?

These replicas are produced as collectible display pieces and are not sharpened to a functional edge. The blade profile follows the correct katana geometry - including the kissaki tip and ha edge line - but the edge itself is finished blunt to meet standard collectible product guidelines. For safe handling during repositioning or photography, cotton or nitrile gloves are recommended to prevent skin oils from transferring to the steel surface, which can accelerate localized oxidation over time. When moving the sword between display positions, support the blade from the spine rather than the edge line to preserve the finish and avoid contact stress on the tsuba-to-blade junction.

What should I use to maintain a gray-handled katana in display condition?

Keeping a display katana in optimal condition requires consistent but simple care. For the blade, apply a thin coat of choji oil or mineral oil every one to three months using a soft lint-free cloth — this prevents surface oxidation without leaving residue that could affect the hamon's visibility. Avoid touching the blade directly with bare hands, as skin oils accelerate spotting on polished carbon steel. The gray ito wrap should be kept dry; humidity is its primary enemy, as moisture can loosen the binding and discolor natural fiber wraps over time. Store or display the katana horizontally or with the edge facing upward in its saya, away from direct sunlight, which can fade ito color and dry out lacquered saya finishes. A silica gel packet near the display mount significantly reduces ambient humidity risk in enclosed cases.

Can lion tsuba katana be used for tameshigiri or test cutting?

Several pieces in this collection - particularly those built on T10 clay-tempered, Melaleuca, or spring steel blades - are constructed with full-tang assembly and sufficient blade geometry to support tameshigiri on appropriate cutting targets such as water-soaked tatami mats or bamboo. However, these katana are sold and positioned as collectibles and display pieces, and any cutting use should be approached with formal training and proper safety preparation. Softer steel options like 1045 carbon steel are better suited to light practice or display only. If tameshigiri compatibility is a priority, look specifically for full-tang construction paired with T10 or spring steel blades, and ensure the handle wrapping and fittings are tight before any use. Regardless of use intent, post-cutting cleaning and oiling are essential to preserve the blade.

How should I maintain the carbon steel blade over time?

Updated Feb 2026

Carbon steel is reactive, so routine care is essential. After handling the blade, wipe it down with a soft, lint-free cloth to remove fingerprint oils that can trigger oxidation spots. Apply a thin layer of choji oil (or food-grade mineral oil as a substitute) along the entire blade surface every eight to twelve weeks. If you notice minor surface discoloration, a gentle pass with a non-abrasive metal polish cloth will restore the finish. Store the katana in its saya in a room with stable humidity — ideally between 40 and 55 percent relative humidity. Avoid leaning the sword against walls where it can fall; a dedicated stand or wall mount is always the safest storage method.