Volume 10 covers episodes 37-40: "The Yamanote Express Incident," "That Man, Shouji Toukairin," "Ah! The Springtime of Beach Volleyball Man's Youth," and "Three Couples' Dangerous Date."
The Yamanote Express Incident:
A Yoriko/Aoi episode. The Chief has promised to only send two of his officers on a mission to catch two wallet snatching thieves who work the rail system. It's obvious he has Natsumi and Miyuki in mind when he makes this vow, but Inspector Arizuka has requested that Yoriko and Aoi take on the job. The Chief agrees, but sends Miyuki and Natsumi along to keep an eye on them in case things get out of hand. And like any good YUA episode, things do get out of hand when the thieves end up stealing guns by accident and hijack the train.
That Man, Shouji Toukairin:
Toukairin is a recent new addition to YUA, appearing in the previous volume as an emergency rescue officer who helps Natsumi rescue the Chief from the top of Tokyo Tower during a bad wind storm. Now he's a transfer member of Bokuto Station, there to train the traffic cops in emergency rescue tactics. After being beaten in an arm wrestling contest by Toukairin, Natsumi sets about to prove herself to him and the station by amping up the stakes for the rescue training.
Ah! The Springtime of Beach Volleyball Man's Youth:
Strike Man and the gang in a beach adventure. The episode is mostly fan service, for the guys and the girls (if they can tolerate a speedo sporting Strike Nan and a trunks wearing Nakajima). Yoriko has concocted a plan to win herself a trip to Hawaii. The beach they are all going to (Miyuki, Nakajima, Aoi, Yoriko and Natsumi) is having a beach volleyball competition, with a trip for 5 to Hawaii for the winners. She pits Natsumi and Miyuki against the unlikely combination of Nakajima and Strike Man "disguised" as Beach Volleyball Man. This way, she thinks, the two teams will make it to the final match together, and no matter who wins, she'll get to go on her trip. No policing in this episode, just the bathing suit clad police officers (including Aoi sporting a bikini, but don't worry, she wears a wrap) goofing off and having fun.
Three Couples' Dangerous Date:
Another off duty episode. Nakajima finally works up the courage to ask Miyuki on another date (helped by the always plotting Yoriko of course) to a local amusement park. Natsumi, Aoi, Yoriko, and the Chief tag along to spy on them. It doesn't take long before their cover is blown, however, and they all end up running around the park together. The Chief finds out about a "Monster Hunt" attraction, which is a fairly realistic paint ball game (the creators must really like paint ball since this is the second episode that includes a game) and they all decide to enter together. The guys who run the game are obsessed with finding the perfect couple with true love for each other, insisting on putting couples under pressure to see how they react. The gang eventually breaks up into the Chief and Natsumi, Miyuki and Nakajima, and Aoi and Yoriko (who I think make a very cute, if bizarre, couple), and set off to reach the goal. But as the gang picks off the monsters one by one, their leader decides it's time to stop playing fair.