Well, I asked for it, and Toukairin and Natsumi are out in full force on this disc, which is solely devoted to building their relationship. And I have to say that this is the fastest moving relationship I've ever seen in any anime ever made. 4 episodes cover pretty much the entire thing; if Miyuki and Nakajima's relationship moved even a 10th of this speed it would actually be interesting. Disc 12 covers episodes 45-48: "A Summer's Day Together," "Toukairin's Challenge," "The Time Limit," and "The End of Summer."
A Summer's Day Together:
Oshou has something he needs delivered to his mother who lives out of town (in what looks like a small farming town). Natsumi and Miyuki, who have the day off, agree to make the delivery. Toukairin shows up while they're visiting Oshou. He seems to be spending a lot of time around Bokuto lately, much to the consternation of the police officers there (who are as clueless as a thumb tack), and keeps showing up around Natsumi. On their way to visit Oshou's mother, he shows up again, riding his bicycle (which he manages to ride at inhuman speeds) with the correct item of delivery, and goes along with them. While Miyuki helps put a meal together, Natsumi and Toukairin set off together to shop for extra food so they don't clear out the little old lady's entire kitchen with their endless appetites. Toukairin shares a little of his past with Natsumi, which only confuses her, then they get caught in the rain together and share a couple of very cute moments. Progress has been made!
A young kendo student gets beaten by a female student and decides he's going to quit kendo all together. Toukairin overhears and challenges the boy and his friends to become stronger. He decides to train them in his own way, and takes them fishing and plays baseball with them (or well, they're throwing baseballs around at least). Meanwhile Natsumi discovers that the reason the young boy was so upset is because he has a crush on the girl who beat him (and she likes him as well). She works with Toukairin to hook the kiddies up by having them attend a traffic safety program at the station.
The Time Limit:
A huge accident has occurred inside a tunnel, involving a pretty ridiculous amount of cars. The rescue workers on the scene enlist the help of Bokuto station to control the flow of traffic around the area, and someone has specifically requested Miyuki and Natsumi for help at the scene of the accident. Guess who? The girls and Toukairin work with the other rescue workers to pull all of the people out of their cars and lead them to safety before all the leaking fuel in the tunnel bursts into flame. They're about to celebrate everyone's safe return when an injured mother declares that her small son was sleeping in the back seat of her car and has not been brought from the tunnel. Toukairin and Natsumi rush inside in a race against time to find and rescue the small boy. Faced with imminent danger, Toukairin finally declares that he cares for Natsumi.
The End of Summer:
Toukairin has been called away from Bokuto (where he has been helping train the officers in rescue methods) to the Himalayas. The station decides to throw him a farewell party. Everyone becomes worried when Natsumi doesn't show up. She didn't take the news of his departure to well. When she finally does show up, hours late, Toukairin, who had stayed to wait for her, invites her out for a night of drinking. They end their evening with one final arm wrestling match, to settle the score, and Natsumi finally beats him. The next day Natsumi goes back to work, and Toukairin heads to the airport. At the last minute, Natsumi finally realizes how she really feels for Toukairin, and rushes off from work to catch him before his plane leaves.