| Can you prove this information of yours isn't false?
This article and/or a section of this article does not cite any references or sources. Please help the Soul Eater Wikia by adding citations to reliable sources. Unsourced material may be challenged and removed.
Shadow☆Star: Zeroth Form - Masamune (影☆星・零ノ型「正宗」 Kage☆Boshi: Zero no Kata "Masamune" in Japanese) is one of the various forms within the Shadow☆Star series and is one of the more powerful forms.
The most powerful form of Shadow☆Star, it is initiated after performing a powerful Soul Resonance. Black☆Star's shadow rises up into the air, before diving down towards Black☆Star, wrapping around his neck and transforming into two long scarves of shadow matter. The Uncanny Sword no longer has a black blade, and it reverts to its original form before it began consuming human souls. Tsubaki can make this form lighter than the average katana for Black☆Star to wield, however, Black☆Star wishes for Tsubaki to make it the weight of a normal katana.
The scarf of shadow matter around Black☆Star's neck has a diverse range of uses. It is solid so it can block attacks and even be used to cut through flesh. It also acts like an extra limb, allowing Black☆Star to pull of impossible manoeuvres without losing balance, as well as catapulting him away from danger. In a way, it acts like Medusa's Tail Snake. It is unknown as to who controls the shadow: Black☆Star, Tsubaki, or maybe even both as their minds are in sync whilst using Soul Resonance. This form is only used against the fight against Mifune and the fight against Noah (Greed).