Forbidden Love Vol.1-2

Princess Mayuka is dispatched to Earth to revive a vital Weapon following her family's overthrow in a coup d'état. While studying Earth's mating behaviors, she seeks assistance from a college student named Yoshizumi. However, she accidentally crash-lands on his roof and is mistakenly taken hostage, during which she is shot with her own weapon. Subsequently, she is brainwashed into believing she is Yoshizumi's younger sister. As time progresses, Yoshizumi develops an affection for Mayuka and decides to aid her in awakening the powers of Akiho, the Ultimate Weapon characterized by red hair, green eyes, and a strong appetite, using basic stimulation techniques.