Moon Blade

 (Tsukiken, 月剣) is the primary weapon used by Yūrei, given to him by his father; The clan leader of Ikiken Clan, after Kōsei proved himself worthy of wielding this blade. While the swordsmith of this particular blade isn't known, it has been stated to the most powerful close ranged tool of his clan.

Appearance
This legendary sword has been passed down through the generations to the Ikiken lineage’s current heir. It resembles a long ninjatō, with a straight blade but with a modified guard. The inscription on the blade’s surface is written in divine characters that are incomprehensible to most humans. One interpretation of its meaning reads: “Praise be the order brought forth from the very edge of chaos.” Unlike a ninjaken, its length is exactly 82 cm (more than 60 cm), while this makes it hard to wield but this also proves quite useful in ranged combat, specially if the wielder wants to avoid taking hits. The cross guard has somewhat of a manji-like shape but the tsuba is curved and jagged. The blade is slightly curved around its tip with three protrusions along the blunt end of the sword close to its tip. The alloy used to forge this blade remains unknown till date but the strength and durability of the sword greatly outmatches that of titanium-steel's, being a lot more denser and sharper, allowing the user to cut his victims in half easily. It is able to cut through most conventional materials including flesh, bone, dense polymers, wood, stone, hard glass, aluminium, iron and some types of metals. The are made from a special metal alloy that can be infused through "chakra flow" with elemental chakra or even Yin–Yang chakra to produce added effects. According to his father, the blades are able to absorb the chakra type of the user, and become the origin of a technique, for the user.