Sangoku Rensenki - Otome No Heihou!
Other titles :
三国恋战记~少女的兵法, 三国恋戦記～オトメの兵法！～, Heihou!, Sangoku Koi Senki, Sangoku Koi Senki - Otome no, Sangoku Rensenki, Sangoku Rensenki ~Otome no Heihou!~
From Iskultrip Scans Yamada Hana, a high school girl, woke up and found herself in a strange land after being enveloped by a bright light that came out from a mysterious book. There, Hana met a young man named Gentoku, and ended up staying with him and his army as "Koumei's disciple"…