I'll be honest, reading the translation, and the context of his introduction, I'm starting to think Denjiro here is indeed Kyoshiro. He was introduced simultaneously with Hyogoro, the former Yakuza boss, and he was seen swindling and playing the money exchange game with the store owner. And his general trickster nature is along the lines of Kyoshiro. Also find it fitting he's introduced as a boy, though that plays into another theory I have.
He even wears similar shades as Hyogoro.
Lastly, I'm really liking young Kin'emon and Tsuru's dynamic. Doubly so that they've been close since childhood. Tsuru's probably the only person who gave a damn about him before the Scabbards and Oden came in to his life.