Volume 11 contains episodes 41-44:
"Round it Goes! The Fiery Patrol Light (Part 1)," "Round it Goes! The Fiery Patrol Light (Part 2)," Bokuto Station Scandal," and "Bokuto Ghost Story."
Round it Goes! The Fiery Patrol Light Parts 1 & 2:
A rare two parter; most episodes of YUA are stand alone. In this set, Bokuto Police Station comes under scrutiny for a series of attacks on drivers by a black car and 2 motorcycles (all driven by supposed traffic cops, and sporting flashing red lights). The attacks occur in Bokuto's precinct, leading HQ to suspect that it's an inside job involving Bokuto cops. I mean they really think it's them. Inspector Arizuka comes down hard, suspending all patrols from the station except in emergency situations. This seems a little odd, honestly. The cops of Bokuto can be rather...unorthodox in their methods, but they're good cops, and they always get the job done (and do it well). There's not anything specific that really points to Bokuto other than it's happening in their precinct. Of course Miyuki and Natsumi, along with Nakajima, aren't going to sit by quietly and let this happen. They take matters into their own hands to hunt these renegade cops down and regain the faith of the citizens they protect.
Toukairin makes an extremely brief appearance in this story. His face is shown in a thoughtful "I have an idea" expression, and he has a phone conversation with the Chief (but you don't know it was him until later as you don't hear his voice), and he shows up at the very end to give the girls a hand. I really wish he had a larger part, though judging by the preview from episode 44, he'll show up in the next volume with Natsumi. Which is great, as Natsumi's been getting action with Nakajima in this volume (she gets more screen time with him in the entire series than poor Miyuki).
Bokuto Station Scandal:
A group of teens has been spying on Bokuto Station. Using a small remote controlled helicopter equipped with a digital camera, the amateur spies take pictures of the gang and post them up on a website. They appear to be fans of Bokuto, and want to show everyone pictures of the cops being "regular" people, to humanize them and show people how kind they all are so they're not scared to approach them. It's all fun and games until the gang spots a particular photo that contains a bank robber they've been looking for - the man's car and face is in the background. It's a race against time to track down the teens and get them to pull the photo before the robber finds them first.
Bokuto Ghost Story:
Must be a Halloween episode, as it is full of several creepy little stories. The gang thinks a ghost is haunting the station and decides to check it out one evening. The Chief warns them not to mix police business with private business, then proceeds to scare the pants off of them (and himself) with stories about ghosts and murders involving the station in the past. They creeped me out a bit, but I'm pretty much a complete wuss, so it's not hard.