Mitsuki Iori’s Hand

Mitsuki Iori's Hand is her physical hand that was experimented on, where it violently mutated to become an independent being. Appearing in the Seraph of the End: Guren Ichinose: Catastrophe at Sixteen manga, after considering Guren Ichinose it was cut down by him.

Appearance
Appearing as a regular left human arm at first, its initial alteration involved the forearm expanding and becoming rigid. The finger's skin appeared the same as before, where they were larger in size with almost talon like nails being instantly formed. Cut off, from the opening at the end, three limb like formations emerged, one positioned where a tail would be, which were strong enough to raise and support a now gigantic hand, much larger than a human.

Three eyes, each with small pupils, had also developed in the palm of the hand. Underneath these, an overtly large mouth could open, which possessed two rows of rather long serrated teeth. Past these the creature had two wide tongues in its spacious and deep gullet, one where a tongue would normally be in a living creature, namely the bottom of the mouth, and the other one on the palate. The light within may indicate that rather than leading to a stomach area, the mouth opened to the other side of its relatively flat hand body to see through the being.

Personality
Even when attacked its curiosity prevented a violent response, where instead it focused on Guren, apparently surprised that he was also a demon. At no point was it hostile, rather in the stage of developing where through no fault of its own, its movements and appearance invoked strong reactions in others.

Background
When Guren refused to use human experiments to cure the poison of the demon curse within him, Mitsuki injected herself as she had the same blood type, A, as him. A small amount of the contents of a hypodermic needle did not seem to have an effect at first. The power was felt initially, where Mitsuki’s left arm swelled under her sleeve. Drastically altered in size, the fingers had grown where they ended with sharp claws.

Through some means it had learned human speech, and was aware it was a demon. Even though Guren had a trace amount of demon influence embellished on his soul from contact with a Cursed Gear sword where his arm was reattached through its power, the hand could sense that.

Story
After the limb was severed at the bicep, it fell to the floor where it grew to a far greater size than Mitsuki herself and Guren. Able to stand on three limbs that had grown to support it, the hand faced them both. Told to die by Guren and struck with his sword, the being was affected by the power of the weapon, and reacted to the strike. One eye was far larger than Guren’s head and focusing on him, the hand was capable of communication, where after discerning what was in Guren, it could see he was also a demon.

Aftermath
Cut apart, the hand lies still with what appears to be blood coming out. After a scientist reached out to touch it, he was warned not to as the hand was said to still be contagious. Curse protective clothing would have to be worn, in an indication of its nature.

Weapons

 * While its sharp nails and serrated fangs could be used offensively, they were not.