Im guessing that this new character is an old aquaintance of Urahara and Isshin that they maybe ditched or lost contact with a long time ago, and now hes back looking for them. Hes got limited information and knows about Ichigo but decides to play some games on him while he looks for Isshin, theres no way that Urahara doesn't know that this guy is in town or that this new guy doesn't know where to find Isshin, just not possible in bleach lol. Im guessing its all a little game to mess with Ichigo and will end soon, then starts the real arc.
Im curious about how strong Ururu and Ginta got. When they were kids Ururu was strong enough to just about kill a shinigami of a seated level, and Ginta could damage an Arrancar, now that their older Im guessing their stronger, but how much hmmmmmm hehe