Sechuu no Hana wa, Gunshin wo Itsuwaru

Mei lost her mother, dumped by her boyfriend...and stabbed by a mysterious sword that fell from the sky. She thought she died, but when she opened her eyes, she was in another world. A world she had seen in the textbooks she was using to teach her students at cram school...ancient China. Everyone calls her "The War God Mei" and looks like she has to save the country by fighting the war! Mei decides to act like the War God, but the beautiful general who came to pick her up looks suspicious...

(Source: MangaPlaza)