It was a period of time in Chinese history where many manly men made many manly legends.
For example, a man named Xiahou Dun was fighting in a battle like any other, then he got shot through the eye with an arrow. Ow. Now normally most men would've crumpled in a heap and died.
Not Xiahou Dun. He rips the arrow out, eyeball and all, and proudly proclaims "Essence of my father, blood of my mother, I cannot throw this away!" and then eats the eye.
While that's pretty manly right there, he doesn't stop at just that. No, he picks up his sword and rams it straight through the stupid bastard who shot him through the eye.
So naturally, Japan has to take this manly tale of manly men and turn into either moe anime girls "fighting" or a complete fanservice anime with panyshots galore.