Because you like The Spirit of the Puzzle in Yu-Gi-Oh!
The last war left his economy devastated, and now Germany is engaged in another war and stuck with two barely trained allies for help. See them in Axis Powers Hetalia.
An alien, a time-traveler, and an esper are following Haruhi Suzumiya, who – unknown to herself – is a near-omnipotent reality warper. See them in The Melancholy of Haruhi Suzumiya.
For Celty Sturluson, it's rather upsetting to be the only headless girl in a city filled with full-bodied humans. See them in Durarara!!.
With most of the people that Sango loved now gone, the only thing she wants is to kill the demon who destroyed her village. See them in Inuyasha.
From secret organizations to alien attacks, Kyon's life has been one weird, unexplainable thing happening after another. See them in The Melancholy of Haruhi Suzumiya.
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.
What Mako Mankanshoku lacks in common sense, she makes up for in sheer optimism and force of personality. See them in Kill la Kill.
After several hundred years of shutting himself out from the rest of the world, Japan's not used to dealing with nations, See them in Axis Powers Hetalia.
After Rintarou Okabe develops the Phone Microwave, some of his fantasies start to seem uncomfortably real. 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.
Years of brutal winters, foreign invasions, and crippling loneliness have left Russia's mental state far from wholly intact. See them in Axis Powers Hetalia.
Fate has forced Amuro into the terrors of war, and he must use the Gundam and all of its power if he is to make it out alive. See them in Mobile Suit Gundam Series.