This is where the story really starts getting good, just like in the anime. The identities of the reborn Shion & Shukaido are finally revealed, while Alice begins to doubt (reject, really) her identity as the reborn Mokuren; Rin's actions are finally explained, as are his erratic behavior and startling powers, and the true nature of what befell the alien scientists is revealed. Surprises galore as children and teenagers struggle to deal with adult problems from lives they're only now discovering they once lived.
It's worth noting as well that many questions left completely unanswered (and bafflingly so!) in the anime are answered here. It's almost as though the writers for the anime were so concerned with squeezing as many important scenes into the series as possible that they left out much of the substance... Rin's obsession with the Tokyo Tower is explained, the reasons behind Rin & Haruhiko's appearances are explained, and Shukaido's motivation is finally revealed!