Here's a summary i found on the net... seems promising
At least it's not the usual science-fiction idiocy that too many times i've found and seems a rather decent story with lots of possibility for serious humor
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In order to save the Earth from foreign invaders and their giant mosters, the Dr Kishida makes what any other crazy scientist of hot blood would do: he constructs to a giant robot - ARIEL - the definitive feminine battle robot!
Unfortunately, his granddaughters reject to pilot it. Apparently they have more important things to do than to become adolescent super-heroines.
In addition, how could one assume that they could be going to study for the entrance examins of their institute when they are taking the beating in battle?
Luckily for Dr Kishida, the things do not go too much well either for the invaders. According to his Earth information it was a perfect objective: exhuberant, pacific, and relatively defenseless. In theory, the planet must already have counquered by a long time.
Now that the war is in a deadlock, the feared Department of Finances is alerting about the seriousness of the excess expenses, and the head of the Department of Internal Affairs has arrived from the Galactic Headquarters to supervise the operations personally.
Has he decided to lose the Headquarters to the Department of Finance or does he have something worse in mind?
The destiny of the world falls to two people: Aya Kishida, one of the granddaughters of the doctor, who could have to leave for the military preparatory school to pilot to powerful (and charming) the ARIEL; and a mysterious foreign call to the so-know Starblast, that could have the power to defeat to the invaders once and for always...