Vampire Bat

Vampire Bat (コウモリ Kyūketsu Kōmori) is a transformation quirk possessed by Keiko Ketsueki.

Description
Vampire Bat allows Keiko to progressively transform into a bat-like form, with progressively stronger echolocation abilities, as well as increased strength, reaction speed, and flight. Her transformation is progressive, and changes range from minor to major as she consumes more blood. Keiko has to drink the required amount of blood in one sitting, as the consumed blood fuels the transformation. If spread out, consumed blood only extends the time she can stay in her current transformation. If Keiko does not consume enough blood to upkeep her form, she starts transforming back. While asleep, Keiko reverts to her human form overnight, but immediately drinks more blood when she awakens.
 * ~ 250ml = Keiko possesses minor echolocation, and slightly sharper teeth. The bat wings usually hidden in the folds of her back emerge, but are useless at this stage. At this level, her speed and strength is equivalent to that of a good, normal human athlete, but nothing that can be seen as particularly extraordinary.
 * ~ 500ml = Keiko's echolocation is fully functional, and her face gains more bat-like features, such as a broader upturned nose, and larger ears. Keiko's nails grow into claws, and her wings are large enough to be used for gliding. Her strength and speed are a match for peak human performance.
 * 750ml+ = Also known as Blood Drive Mode, Keiko is practically full bat-person and near unrecognisable. Her wings are fully functional and can be used to fly, her claws sharpen further and become useful for grabbing and gripping onto things, and her fangs elongate out of her mouth. The maximum range of her echolocation also increases further.

Because of the nature of Keiko's quirk and the upkeep of blood she must stay on top of, she is able to drink large amounts of liquid, and is often thirsty. Keiko favours Type O blood, on the grounds that it taste better to her. Keiko's quirk does not activate when she drinks her own blood.

Usage
Vampire Bat increases Keiko's versatility and raw power in combat, and can be used offensively immediately, provided Keiko is in a strong enough form to take on whatever danger she faces. While in a passive or low-blood transformation, Keiko prefers to use her knives to attack opponents. While transformed, her claws are more than enough to deal debilitating slashes to her opponents.

Keiko's wings grow with progressive transformations. In her low-blood state, her wings can only be used for gliding, as they do not possess the wingspan to propel her upwards. This forces her to jump from tall buildings in order to get any significant mileage from her wings, but she still can use her wings to glide short distances, traversing declines in terrain quickly. In high-blood states, her wings are large enough to achieve self-maintained flight, and Keiko can use them to fly at incredibly quick speeds, though she cannot go very far by herself through her flight alone and must rely on a mixture of flight and gliding to travel long distances.

Super Moves

 * Giga Drain (ギガドレイン): Keiko grapples enemies and stabs them with both bloodletters, gaining a prodigious amount of blood and leaving targets severely weakened in the process.
 * Let them Bleed (させる): Keiko bites foes, leaving them with large, gaping wounds. Her saliva additionally acts as an anticoagulant, making these bites especially dangerous if they pierce vital parts of the body and they are not tended to in time.