Been watching a bit more of Kamen Rider Den-O (up to episode 14). Perhaps I can recognize voices better than faces since as soon as I heard Ryutaros speak I was like "Hikaru or Kaoru?" and a few sentences later I was sure it was the same voice actor as Hikaru from Ouran. In addition to having the same voice (spoken mostly in the same tone/inflection too), both of them act like kids, have sadistic humors, and can wheedle and cajole like the best of them. (Okay, Hikaru probably wouldn't physically harm or kill someone, but I find them more alike than not.) And sure, I admit that I would probably not make the connection at all if not for the same voice actor, but they do have the same voice so it's fair game for me to attempt to compare them (superficially perhaps).
I know this is not news but I mostly avoid spoilers so I was glad to still have Ryutaros' voice as a surprise. That and his imagin form, which I'd never seen before watching this set of episodes.