Kuro is a clone who split off from Ilya and incarnated in the form of a certain Heroic Spirit.
However, Ilya also claims to be the older sister, leading to endless sibling quarrels that look like someone yelling into a mirror.
Ilya rejected Kuro at first, but Kuro eventually came to live in the Einzbern household.
Her cover story claims that she’s Illya’s cousin, but the resemblance is so uncanny that they are often mistaken for twin sisters.
Upon their first meeting Ilya’s foster brother Shirou mistook Kuro for Ilya. This was understandable since he had no idea Kuro existed, but it was a great shock to Ilya that her brother couldn’t tell them apart.
Kuro does not know the identity of the Heroic Spirit whose form she has borrowed. She has only inherited the fighting skills that he refined.
She wields her formidable combat powers with reckless abandon. Rin saw this as a threat, and inflicted on Kuro a curse of shared pain perception. Kuro’s shared pain with Illya was meant to deter her from targeting her twin, but the trifling curse meant nothing to the little devil.
An exquisite technique of a certain Heroic Spirit.
The user projects three sets of the male and female paired swords, combining throwing and slashing maneuvers to execute an unavoidable combination.
Kuro also teleports behind the enemy in conjunction with the technique, making her attack difficult to predict even with Mind’s Eye.
The only ways to defeat it are with an omni-directional defense, or by ignoring the damage to make a suicidal assault on the user.
Kuro, who unexpectedly manifested as a Servant-like being without a Master, always requires magical energy.
Thus, she resupplies via mucous membrane contact as a quick and easy method that requires no contract.
An unguarded victim will suddenly oneself thrust into a kissing scene by the brown little devil, without a care for the time or place.
“But don’t get me wrong, it’s just a medical procedure,” she says. Oh, that makes sense.
Ilya’s sealed qualities and memories grew denser and more complex until they condensed into a distinct personality: Kuro.
Kuro is aware of this.
She knows that it’s a miracle that she can even exist, even if it might not be in the way she wanted.
Still, Illya and her family accepted Kuro.
The warmth of a family she believed had been stolen from her was still there after all, waiting for her.
Thus, her birth must have had meaning.
Kuro will lecture her unreliable little sister, defeat her enemies, and show her the way.
Once, she thought her little sister was behind her. But before she knows it, Ilya will surely surpass even her big sister, and reach for the light of the distant stars.