Han Yu can't be gone.
Xi Zirui refuses to believe it.
His plan wouldn't be just to sacrifice himself. Not after Xi Zirui has told him that the whole point of him hopping into these worlds is to be with him.
He looks anxiously at all the debris floating gently in the empty space between the two ships, looking for any sign of Han Yu at the same time he dreads finding it.
Only belatedly does he realize that Little Thunder is still meowing at the depressurization chamber before the hatch door.
Xi Zirui presses a button in the wall and the depressurization chamber slides towards the opposite wall, flattening itself and revealing the unobstructed path to the hatch door.
There's nothing there.
Little Thunder starts scratching and meowing at the metal hatch door now, stopping only to sniff it for a moment before continuing his frantic scratching.
His determination is even more noticeable due to his missing paw.