In real life, creating three versions of yourself so you can pit them against each other is a sign of insanity and multiple personality disorders. In Tenjima, it's what Chirikai does when he can't make up his mind.
Or when he needs to confront his feelings. Ha. Tenjima is a whacky place where the conversation isn't just a metaphor. I mean, it is a metaphor, but the pristine self is also joking about taking a chunk out of Chirikai and leaving it somewhere to rot. Literally.
You can only do shit like this in fantasy, seriously.
But in all seriousness, this is actually a pretty dark chapter. If it's going to speak to anyone, it will speak to people who have struggled to get over something. Chirikai's pristine self is something he admires, even if it's a past version of himself. The pristine self is Chirikai before he lost his mother, before he fell in love and lost Asuka.
He's also like the best friend who's slapping him on the back and giving him a beer, reminding him of all the others Chirikai can be with.
The pristine self is the voice in every person's head who tells them, desperately, that they have to change, and the mind accepts this, but the soul ignores.
But the pristine self is also nostalgia for a better time. A time before hurt, a time before failure. A time when things were simpler.
So Chirikai is off chasing that. Who knows what he'll find.