Panel 1: Note that the “four-footed cane” wielded by the Elderly Dude ninja in the background is not, repeat not, a proper ninjutsu weapon, but I found it funnier to have him carry the cane as is, rather than pull a more ninja-appropriate hidden chain or blade from it.
Panel 3: As we’ll see, this clan of ninja are an unusually tough and pain-resistant breed of shinobi.
Panel 4: Worry not, we’ll soon see what the Japanese word nukenin means—in fact, on the very next page!
-Adam Warren