Shadow Weapon Mode: Shuriken, known as Dark Arm Mode: Ninja Star in the anime, is one of the Demon Weapon transformations of the Demon Shadow Weapon. With the combination of the power of the Uncanny Sword, it's upgraded version is known as Shadow☆Star: Second Form - Leaf of the Moonlit Night (影☆星・弐ノ型［月夜葉, Kage☆Boshi: Ni no Kata Tsukiyoha) or simply Leaf of the Moonlit Night (弐ノ型［月夜葉, Ni no Kata Tsukiyoha).
Ordinarily, the Shuriken form is quite large, about the size of a wheel, and it takes the common fictional shape of a five-point star. It is largely light grey in colour, but has three dark grooves along one side of each point, the other sides having a dark grey edge. Two yellow dots are seen in the middle of the Weapon form above the shuriken's central hole, resembling a face.
Transformed into it's more advanced variant, a large four-pointed shuriken, constructed from four black (and vaguely leaf-shaped) blades with ornate white patterns on them extending outwards from a wide circular ring acting as the weapons center.
It can be be thrown with considerable force at a target, using the high speed of the rotations and sharp blades to easily slice through the majority of objects. When used, it easily cuts through Crona's Screech Delta shock waves. However, the true potential of this ability lies in the significance of the large hole present within the ring. In addition, by inserting a hand into this specific section, A Meister's fist is immediately coated with a smooth black substance that is accented by ornate white patterns, which proceeds upwards with the shuriken to just past his wrist. After this process is complete, Black Star is able to release a substantially powerful blast of energy, which not only causes a distinct extension in the surrounding blades but also emits a significant conclusive force directed forwards. The extent of this blast is such that it can even damage a hardened layer of Black Blood. The shock waves seem to shoot through the blades as well, as seen when Black☆Star first uses it.