Exactly. And Hattori-niichan is a good detective. He figured it out a long time ago. [He had to say it. He said Hattori would kill him if he got her involved. Or at least he suspected the other world, especially since he hadn't even told RAN the truth.]

I really don't like lying, Kazuha-neechan. [Which was true. Even know he was feeling guilty for lying.] But I know enough to know there's danger. If you had kept asking, I would have told you the whole truth without being able to stop. As long as you don't know, you're safe. [As long as she didn't follow them into a dangerous situation, anyway.]