u/The_wolf_eater_47

This will be my first attempt at analysis, after recently finishing Usogui it is still continues to amaze me with just how much there is to discover.

The shared hallucination of Baku and Yakou in the second stl will be the main topic here. After Baku managed to realise his leap second plan, he and Yakou both saw Kiruma standing up after surviving his last penalty. This scenario would mean extreme disadvantage to Baku as he had only a couple more seconds in his cylinder left.
This scene is different from the protoporos nightmares, it’s a comfortable lie that both Yakou and Baku would be contented with. Both of them feared he won’t survive so much that they deluded themselves into thinking he did stood up.

For Yakou, this scenario would be easier to accept, as he had already felt guilt for killing Tatsuki, he didn’t want to face truth, now that he had to take Souichis life too. Both father and son would die from his hands. But also, he wouldn’t have failed to revive Kiruma, even though he was exhausted and with his arm shattered, against all odds he would still succeed as a perfect referee.

But it can seem strange as to why Baku saw the same thing. After all, if Kiruma had survived that round, Baku would lose would be almost guaranteed.
But let’s look at the vision and its implications once more.

Firstly, Baku wouldn’t be happy with Kiruma dying (obviously). Secondly, Kiruma had already reversed back to being Hal after his second death penalty, we can see it clearly from Baku’s reaction in chapter 521. (They both smile)
The game continues not just because of strict Kakerou rules which would prevent stopping before one of them was dead, but also because Baku is a “pest” and won’t give up his life, even if it’s to guarantee that his best friend lives on.
Back to hallucination, near the end Kiruma tells Baku “don’t look back” that part was the hardest for me to make sense of, but I think I managed to make a decent enough explanation. After his victory, Baku laughs manically, he seems extremely proud to finally win over his ultimate opponent “killing you with my own hands” “no matter what”. If we look past all the aura, it seems very unnatural for Baku to act like this, that because, in that very moment, Baku lied.
His lied that he didn’t cares about Hal dying, that he only viewed his as a strong opponent, that is the moment when his hallucinations started. Him calling Hal a liar (chapter 531) is actually meant for himself. In the end he devours his own lie, he is now serious and proclaims “I know, Hal, I won’t look back.” In that moment he truly faces the reality and decides he will try to revive Hal. He “doesn’t looks back” not because he doesn’t care what will happen to Hal, but because he will take fate into his own hands and make Hal live.