Ariel (Light Novel)

Through a series of unfortunate events, Earth was suddenly attacked by Albert Houser, owner of the offworldly Gedo Corporation. To expel the beast-like invaders, one man created Ariel, a woman-shaped mecha designed to defend humankind! But this mecha required a special kind of pilot, and who better for the job than.. his granddaughters?! Now, to save the human race, Aya (who would rather be studying),  Mia (who would rather be playing sports) and Kazumi (who actually likes the job) must pilot the feminine Ariel, before Houser can complete his nefarious plan!