Hero in Another World

As the final battle in Puzzle City occurred, Cale managed to stab the World tree branch to White Star. But who would have thought that that bastard would choose to blow himself up to take Cale death with him? Cale died, but why did he wake up in the body of a child instead?
"Cale-nim...."
"Cale...."
"what the fuck-?"
"......Choi han? Bud? Archie?"
And why are these three people here too?!