You Promised Me Darkness Vol. 1

Approximately every 75 years, Halley's Comet orbits around the sun, and every time this happens people around the world are born with incredible abilities, special auras that grant them supernatural skills, but these very auras can also be cursed. Yuko and Sebastian, two siblings with special auras find themselves constantly on the run from an evil being, simply known as the "Anti-Everything", who feeds on these special auras, and gets stronger with each intake. This being is obsessed with these siblings auras and will not stop until he feasts on them.