Because you like Norman Bates in Psycho
The Sohma family is just plain cursed, and Yuki Sohma has to learn to live with it – or so he thinks. See them in Fruits Basket.
Konata Izumi has a live-now, worry-later view of the world. See them in Lucky Star.
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.
Kagami Hiiragi keeps her grades up, helps at Takanomiya Shrine, serves as class president, and hangs out with her friends. See them in Lucky Star.
Using a bracelet his late mother gave him, Apollo Justice can sense when other people are nervous based on even the most subtle signs. See them in Ace Attorney Series .
Yuri is living in the afterlife, which takes the form of a high school where no one dies. But if you follow the school's rules and live a "normal" life you vanish. See them in Angel Beats!.
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.
The personification of America is all about superheroes, hamburgers, and spreading democracy and justice. See them in Axis Powers Hetalia.