Blackthorn is a long furred black tom with green eyes.
- Blackthorn was born into a far-away group of shadow-wolf Youkai, and was known as Bakusaiga.
- His father Tenseiga was the leader of the pack, but was killed by his half-brother Tetsaiga, and Blackthorn and all his other friends were turned into cats matching their fur color, but his sister, Oakfeather, and his other relatives died in battle.
- Blackthorn escaped the tyrant Tenseiga, and found his way to the forest, and overheard clan cats talking, and some names, and decided to make a simalier name, Blackthorn, and then went to the rogue alleys, where he had a slight crush on Paw.
- He is very easy going, and likes to joke around.
- He then learned of Gaara, and tried to fight him a few times, but Kovan then tried to kill Blackthorn, but he lived, leaving him and Gaara wounded.
- Blackthorn later asks why Kovan would kill him to save Gaara, to which he replies that Gaara has Shukaku, the sand spirit.
- Blackthorn understands, and roams the forest, still slightly infactuated with Paw.
- Later on, Blackthorn goes on a quest to kill Tenseiga and free his old pack friends, and Gaara comes with him, and together they kill the giant Shadow-wolf Youkai.
- Twilight falls in love with Blackthorn, as does he, but he still has feelings for Paw, but then Twilight dies, and goes to Starry Skies and takes Lightning as a mate.
- After her death, Blackthorn is angry, and attacks Gaara again, and turns into a Shadow-Wolf Youkai, but is defeated, and is injured for a moon.
- During this time, he stays in Kakashi's den, unable to sleep in his and Twilight's old den, because he is haunted by memories of her whenever he attempts to sleep there.
- He enjoys the company, but decided to leave the den and make his own den on the outskirts of the forest.
- He recovers, and apologizes to Gaara for attacking, and becomes more distant from the other cats, still grieving for Twilight, and angry with Lightning.
- He likes to take long naps, and eat plenty, and usually keeps to himself nowadays.