Koihime Musou ~A Heart-Throbbing, Maidenly Romance of the Three Kingdoms~

Time travel? Are you kidding me?!

I eagerly rushed out of my dorm to try and catch a burglar who snuck into my school, but next thing I knew, I was laying in a vast, open prairie.
"What the hell?!"
But my amazement didn't last long before I was surrounded by a group of men armed with glistening weapons!
"Leave your clothes if you value your life,” What era is that line from?!

I tried to resist them, but they started spouting gibberish before swinging their weapons at me.
I thought, "This is it for me!"
But then, a black-haired beauty appeared before me. She agilely swung her huge spear, and sent those men packing. As I respectfully thanked her, she began to name herself.
"My name is Kan'u. My Lord, may we fight together and quell these wars?"

[From MangaGamer]