Number 7 of UQ Holder's immortal squad, Numbers. Touta is a cheerful and optimistic 14 year old boy with many dreams. He was raised by Yukihime after his parents died. After being mortally wounded while protecting Yukihime, he drinks her blood and is transformed into an immortal vampire. His weapon is the Gravity Blade, a sword that can have its weight increased or decreased thousands of timesfold according to the will of its user (actually a adjustable dial). His grandfather was Negi Springfield, a legendary magician and Negima's protagonist.
(Source: Wikipedia, edited)