Kokoa Shuzen

Kokoa (Koko in the English manga), is the younger half-sister of Moka Akashiya. She arrives as a first-year student to Yōkai Academy. Like her sister, Kokoa is also a vampire, but her powers are not sealed. Being younger, Kokoa is not as strong as 'sealed' Moka, but in spite of this she is able to carry the Transformer Bat, named Batty (also Nazo Koumori and Kou-Batty), which she was going to give Moka for her tenth birthday. It was too heavy for Moka (about 200 lbs), so Moka passed it up. Kokoa kept it, and is able to wield it herself with enough strength to make herself formidable.