Because you like England in Axis Powers Hetalia

The vampire that killed Zero Kiryu's family also infected him, and he starts to crave blood, much to his horror. See them in Vampire Knight.

For the sake of science, Kurisu Makise will persevere no matter how deep into the dark secrets of the world she finds herself. See them in Steins;Gate.

After alien Haruko rides in on her Vespa, giant robots spouting from Naota Nandaba's forehead soon become the least of his worries. See them in FLCL.

After Rintarou Okabe develops the Phone Microwave, some of his fantasies start to seem uncomfortably real. See them in Steins;Gate.

Shana is a red-haired warrior with a black-and-white worldview. See them in Shakugan no Shana.

If Anna Liebert could remember her past, maybe she would know who she is. See them in Monster (TV Show).

Firo Prochainezo is swept up in a world of mysterious women, alchemists, and rumors of a wine that makes it drinkers immortal. See them in Baccano!.

A laid-back wanderer, Ginko has an empathetic, open-minded worldview. See them in Mushishi.

The main priority for Nagisa Hazuki is making sure that everyone has fun. See them in Free! Iwatobi Swim Club.

Konata Izumi has a live-now, worry-later view of the world. See them in Lucky Star.

He's the great Black Star, and he's come to assassinate you. See them in Soul Eater.

Everyone is just a chess piece, and Izaya Orihara is a master player. See them in Durarara!!.