He is Tsubaki's meister. He comes from a family of ninjas (The Star Clan), which explains the star on his shoulder. He uses ninja tactics. His biggest weakness is that he is a total show-off and thinks that he is some kind of star, which he happily proclaims, defeating the purpose of the ninja arts. The few times he uses his ninja stealth is when he peeps on Tsubaki (which normally ends up with him yelling and showing his whereabouts upon seeing Tsubaki's nude body) when she is bathing, or when he finally takes the fight seriously. His delusion of stardom is so great that he constantly gives out autographs that nobody wants. Black Star hates it when someone gets more attention then him and will show them who the real star is. He is also able to use his soul wavelength in hand-to-hand combat. Dr. Stein stated the painfully obvious when he said Black Star's was "a terribly self-absorbed soul". Black Star comes from a long line of assassins know as the Clan of the Star, and they would do anything for money, making them enemies in various places. Due to their actions, thirteen years ago, the entire clan was exterminated by Shibusen, while Black Star, just a newborn then, was taken in by Shibusen. Despite this, Black Star bears no malice over this, but thanks to his clan, when people the clan attacked notice the tattoo on his right shoulder they will chase him out by any means. His favorite number is one, most likely because he considers himself to be number one. Due to a few of defeats he's received Black Star has started to doubt his skills and seems to have become obsessed with gaining power (like his father White Star that became a kishin because of it). He travels with Tsubaki to her home and while training enters the spirit realm within Tsubaki's sword form. There he confronts the spirit of the sword (possibly part of Masamune's soul) and comes to realize that he is walking the path of the kishin. Black Star overcomes his doubts and finally finds peace with his soul and unlocks his true soul resonance with Tsubaki.Attacks
Black Star has attacks he can use with and without Tsubaki, which makes him more versatile then other meisters.
* Shield Star:
By using Soul Resonance with Tsubaki in Scythe Chain form he creates a shield for defense.
* Trap Star:
By placing the chain of Tsubaki's Scythe Chain form in a star shape on the ground anything that enters will by sensed by Black Star and bound in the chains before they can escape.
* Speed Star:
Created by Black Star to move at highs speeds (mostly for dodging attacks).
* Hissatsu Kokusei Big Wave (Deadly Black Star Big Wave):
A powerful attack that requires Black Star to use a fighting style similar to Dr. Stein's Soul Purge. Initially it starts with an elbow strike to stun the enemy, then a powerful punch which sends a large amount of soul energy through the opponents body. This technique was first used on Mifune by of which he was defeated.
* Soul Threat:
This attacks is like the soul purge but with more power behind it.
* Soul Threat Planet Destruction Cannon:
This is an even more powerful version of the soul threat, its strength is high enough to push back a strong opponent like Mifune with one hand.
* Shadow Star:
This can only be used with Tsubaki's Demon Blade form, it grants a boost of speed and power while a Shadow Puppet is in front of Black Star to attack anything in the way. (This attack covers Black Star with tattoos). In the manga, it has been revealed that extended use of this technique is slowly killing him, but he refuses to accept this. Later after ridding his heart of despair, Black Star is able to invoke new forms with Shadow Star called Katas.
* Shadow Star:
Endgame Cleave: While using Shadow Star, he combines a dash with with a multi-hit slashing combination.
* Shadow Star, First Kata, Black Chain:
While using Shadow Star, Black Star transmutes the sword into a wider sickle-like blade with a long black chain attached to the hilt. The sword can be swung like a blade-whip.
* Shadow Star, Third Kata, Absolute Shadow:
While using Shadow Star, Black Star transmutes the sword into a large kunai-style dagger. Using this technique, Black Star moves with the speed of shadow creating clone-like afterimages.
* Shadow Star, Fourth Kata, Dark Limb:
Using Black Star's soul energy, Tsubaki can take control of one of Black Star's clone afterimages created by the third kata and fight as a team.