Now onto the review!
Having watched the anime before reading the light novel, I came in pretty much expecting to not be surprised--and then, to my surprise, I found myself surprised.
One of the first things I discovered while reading the light novel is that the anime leaves a lot of content out. I almost feel like the anime only has about half the original content of the light novel. It makes sense, considering anime are given a certain number of episodes and therefore might not be able to show everything, but I was still surprised. That being said, it was a very pleasant surprise.
I think what I loved most about this particular volume was how we get to see more of Toma. In the last volume, Toma lost his memory at the very end. In this one, Toma is trying to recall who he was and wondering about the many connections he has. It's interesting to see, not only because he's worried about not knowing who he was before losing his memories, but also because he hasn't really changed much in personality.
Another thing that's interesting are his feelings toward Index. The bond he and she share is something he cherishes even though he doesn't know why. He wants to protect her (no surprise, considering he tries protecting everyone he can), and is worried about what would happen if she discovers that he lost his memories. This also causes him to feel guilt, stating that, whenever Index looks at him, she's looking at the Toma who retained his memories, and that he is not the Toma she remembered.
All this being said, the second volume of this series was fun to read. It had action and comedy, magic and science, and all of the things I've come to expect from the Shonen genre. Reading about it in book format as opposed to anime and manga is really just the icing on the cake for me.