[Died once before? As if Light won't ask about that later, because that's not just a little detail that you skim over, Kaiba. Another question slotted nicely into his mind, to be pulled out not unlike a file later. Because, obviously, Kaiba is quite alive -- if there's a way to escape death, even if it was exclusive to a world that wasn't his own, Light wants to know.

Judge, jury, and executioner though... Well, naturally.] Hmph. If a man is suited to play all three parts, then why shouldn't he? Not everyone has the willpower nor the [insanity???] determination to accomplish what I want for my world.

[Kaiba got it in one. Light is a fanatical idealist, a smart one, making him all the more dangerous. But fortunately, he'll be spared the "God of the New World" speech for now. Small miracles.]

An item? Ha, you're quick to make that deduction; that, or it's just a shot in the dark based on a snippet of conversation. [Either way, he'll explain in broad strokes.] It's a shinigami's notebook. If you write down someone's name and know their face, you can orchestrate their death as you see fit.

Though I wonder how well it would work against someone who's just prone to coming back from death?

[Told you he'd loop it around.]