Eisen was flapping his wings, trying to keep himself suspended mid-air as he was thinking about who of the two Guards he should fight first and foremost. That was because together with that, he would make the choice of which place he would go to first as well.
And in the end, the old man figured that it really didn't matter too much, and approached the one that he was most curious about, the gate to heaven that had the pitch-black Guard standing on the gate upside-down.
He approached it while flying, and the moment that he was underneath it, he was being pulled toward the gate, as if the direction of gravity changed all of a sudden. Unable to react perfectly in time, Eisen fell onto the gate, and pushed himself off the 'ground' after being hurt a little bit. It was just a bit of a bruise though, so nothing serious.