This power of 16,381 units was then stored within his body for future use.
That future happened to be less than a second after he was hit by the attack. In that brief period before he used the stored power, he sprouted wings from behind him, then he shot forward towards the slow giant.
The slow giant was about to get too close for his flak gun to be able to target her. If there was someone driving the airship to create distance between them, he would be able to bombard her all he wanted. Unfortunately, he was the only one in the airship.
Since he couldn't do two things at the same time and since he didn't dare give up the flak to control the airship and make it move back to create some distance between them for fear that they would take advantage of that time to board the ship, he decided to deal with one of them with his full power first.
