Despite the fact that he can be either a jerk, a royal pain in the ass, or both, this episode shows that Daisuke does actually both care about and listen to Haru. While he's shown evidence of this in the past, there are two very specific incidences of it in this penultimate episode that really make the point, and that both revolve around the trauma in Haru's past is what truly make them work. That they bookend the action is really just the icing on the cake.
Of course, we could make the argument that the first time, when Daisuke suggests Haru to drop a container on Shigemaru's henchman instead of attempting to shoot him, doesn't show all that much sympathy for what's going on. He's locked in a struggle with the bad guy when he spots Haru hesitating to shoot (and in all fairness, it would have been hard to pull off without hitting Daisuke too, even without Haru's particular issue), so he just comes up with a solution on the fly that doesn't involve a gun. Somehow he doesn't think that Haru's actual issue may not be “shooting a gun is scary” and instead is “hurting people is bad,” but if nothing else, this sequence definitely shows that to be the case. Daisuke's upset that Haru didn't drop the container directly on the guy; Haru's aghast that Daisuke would even think that he would. But that's never been Haru's thing – even during The Incident in the past, he was shooting to wound or disarm, not to kill, and let's face it, dropping a shipping container on a guy really should have disabled the villain even if Haru aimed it so as not to kill him. (Personally, I'm thinking it was largely up to chance – it's not like he was playing Tetris; there are actual physics involved here.) But the moment does give Daisuke the chance to think about what might actually be going on. Thus, when the next moment arrives, he knows what to say: Haru's a civil servant, yes, but before that he's always been a hero, and that didn't change.
That, more than anything else, is what Haru's needed to hear for the past few years. Not “you'll pick up a gun again,” nor “you'll get over it,” and certainly not “you're not a hero, you're a loser.” It was his sense of self-worth that really took the hit, and when his former partner's anger and frustration at something he couldn't emotionally understand made him lash out at Haru, it just made it worse. From episode one we've seen Haru do his best to help people or to save them – more often than not from themselves. That's who he is as a person, and that's why he's not willing to let Daisuke go off to confront his father in some sort of ill-fated family feud that might end up with them both dead. Haru is going with him to make sure that he can get Daisuke back alive.
All of that almost makes the moment when Haru shoots his gun (at a pipe, not a person) feel anti-climactic, although of course it doesn't. But the more important takeaway from the moment (and the episode) is that Haru and Daisuke are actual partners, not “cop and rich guy.” Whether they're friends or not is perhaps less important – and Daisuke really is at his most deliberately abrasive in this episode – but their relationship provides a solid backbone to what is otherwise an action-heavy caper that relies heavily on Daisuke's fictitious technology and the world's snazziest container ship. It helps that there are also some really nice visuals in the episode, too – Haru dangling from a ladder on the ship, the shot before he and Daisuke get on the helicopter, Daisuke standing in almost supplication with the handcuffs before his father, and the pink-haired detective (whose name I never did catch) standing off to the side with an armful of bristling weaponry are all just really good images. The helicopter moment is especially good – it just screams “heroes off to their final battle.”
Hopefully it'll only be final for Shigemaru. I'm still holding out hope that Chō and/or Takei are still alive (the ambulance did have its lights and sirens on, which wouldn't make sense if they were transporting corpses), but either way, it's just about time to find out where all of this ends.