Ah, yeah, I've heard of that too! That's something you can do even if you don't have modern technology, after all.

[ And while subterfuge wasn't exactly necessary anymore by the time he got old enough to use it, Inigo still remembers seeing examples of it when he was much younger - if not just in heroic stories. ]

Like switching around the letters when you're writing! [ He looks a little proud. Maybe it's dumb to look that way over just.. knowing something of what Senku is talking about, but considering how smart Senku is, it already feels like a big accomplishment to Inigo. ]