All major villains either want to take over the world or blow it up. When someone paints up their face, they mean business. Everyone in Japan has excellent singing voices. No matter how many times you rebuild, Tokyo keeps getting destroyed in a massive fireball. The martial arts expert is always defenseless against a slap from the girl who loves him.
Food is a powerful motivator.
When women are sent out to fight the bad guys, there's always a hunk busily watching over them, often in secret. The longer it takes to say what your punch is called, the less effective it is. The more possessive a woman gets, the less likely she will end up with the man of her dreams. Extraterrestrial, demons, time travelers, etc. The fate of the planet rests in the hands of the seemingly normal high school student.