Mode: Chain Scythe (モード「鎖鎌」, Mōdo "Kusarigama") is one of the Demon Shadow Weapon's weapon transformations thanks to the Multi-Form Ability. After unlocking the power of the Uncanny Sword, it gains a more enhanced and powerful form dubbed Shadow☆Star: First Form - Chain of Blackness (影☆星・壱ノ型「鏈黒」, Kage☆Boshi: Ichi no Kata "Rengoku") or simply Chain of Blackness (壱ノ型「鏈黒」, Ichi no Kata "Rengoku").
Mode: Chain Scythe appears as a long metal chain with each end of the chain tipped with a yellow handle that has a small double-edged and double-pointed scythe blade attached. Three dark grooves appear below each blade. The weapon is also adored with yellow dots on the handles, making them appear as if they have eyes.
In its Chain of Blackness transformation, it appears as a long black sharp sickle-blade, with white ornante patterns on it with a handle attached for the wielder, accentuated with three short spikes. A long black chain, composed completely out of Black Star's shadow, circles Black☆Star twice before it ends at the ground where his shadow is. The blade on the Chain of Blackness is long enough to be wielded as a sword due to its original form as a chain scythe.
The Chain Scythe form can be used in close-range combat, and also long-range as the scythe blades can be thrown at an opponent as an attack, or as a means to trap them to make them wide open for a close-range attack. Tsubaki's Chain Scythe form is also used by Black☆Star to execute a number of other special moves. The chain on this Weapon form can alter, becoming long or shorter.
In its Chain of Blackness form, it is capable of being thrown towards the opponent in the form of a long-range attack. Since the chain originates from Black Star's shadow, Black Star can still control the trajectory of the blade, even if its thrown a great distance away. There is always a part the chain that encircles Black Star wherever he is, giving him protection from assaults from all sides.This form is first used in the final fight against Mifune. Although Black Star manages to slightly wound Mifune with Chain of Blackness, he quickly switches to another form when he finds that sheer power is not enough to counter Mifune's Infinite One-Sword Style.
- In the Book of Eibon, when Tsubaki is transformed into a male, her Chain Scythe form, according to Black☆Star, looks a bit more unrefined to suit Tsubaki's masculine appearance. The scythe blades lose their double points and curve smoothly in a similar manner to Soul's scythe blade, and is also much broader, and two bolts are screwed in on the handles instead of the yellow dots.