I can't believe they have been together all this time and Takaba knows as little as we do ...

Why would Aki tease Kuroda? Or vice versa? They don't have that kind of relationship. They actively dislike each other. On the other hand, it has been firmly established that this is the way Aki and Asami talk to each other. No, it's not strictly asking for information on Asami's part but just the sort of teasing back and forth that always goes on between them. Add in the history of Asami questioning Aki's abilities as a photographer and the fact that this dialogue is kept separate on the panel from what Kuroda says and it's pretty clear that this conversation is between Asami and Aki. But you need to believe it's between Kuroda and Aki because it shores up the image of Kuroda that you have formed in your mind but that doesn't exist on the page.

I'm not saying I don't believe that it's "more than a business relationship," just that it's not at the level of intimacy where Asami would regularly accept Kuroda's interference in his love life. There is more than one level of intimacy beyond "business relationship." Hell, Asami fucked the Hong Kong cop and they had a warm "more than a business relationship" conversation but do you think Asami would take relationship advice from him? No. Do you readily accept such interference from every single on of your warm acquaintances? No. Neither, I imagine does Asami. In fact, I'd doubt Asami has anyone in his life he allows to make such observations to him. Proof: the black look Kuroda receives. So no, that level of intimacy does not exist between them. Again, this is something you are trying to convince yourself of because you want to believe something about Kuroda that has not yet been demonstrated or made clear in the manga.

When I see it, I will acknowledge it. But so far, it's not there.

They discuss Sudou because that is the specific reason Kuroda came to the penthouse. He is helping Asami cover up what happened with the diet member. Kuroda is serving Asami in this capacity so they have to talk about Sudou. The problem with Sudou is part of Asami's business, not his personal life, so that is very much part of the business side of their relationship.

Kuroda does not work for Asami. He is a prosecutor, and talks of it not being bad to have Asami owe him a favor. Kuroda would die for Asami, not because he is a loyal subordinate, but for some other more personal reason. Kuroda may have come to give Asami information, but he does more than that. He discusses strategy and questions Asami. Subordinates don't do that. Subordinates respectfully report and wait for further orders.

Kuroda questions "Ryuichi" comfortably, as if Kuroda has the right to talk that way with Asami. Kuroda questions how Asami would use Aki. Kuroda questions how Asami would use Sudouh. Kuroda questions whether Asami can trust the loyalty of Asami's men--not including himself in that number. Asami answers about people being loyal as long as they think they will get what they want is followed by a gift--but that gift is very personal, as well as something Kuroda had not expected. It's a sort of wry humor, a friendly barb between men who understand each other and share affection. Kuroda is not doing what he does for Asami's gifts. Asami's gifts are Asami's way of showing his genuine regard for Kuroda without being so crude as to say it.

If Kudoda is not a relative or good friend, maybe he is the man who gave Asami the gift of leather bondage gear? I don't see them as lovers myself, because they seem too similar. Both think of strategies, anticipating how others will act. Both sometimes use use a type of humor that may seem harsh or rude if you didn't guess what was behind it. Neither one wants to be seen as weak, even after being shot. They seem to have very similar outlooks on life. They also look similar to me, but that could just be the style of art.

Why would Kuroda and Aki tease each other? Because of what they had just been through together. They are warming up to each other, if a bit grudgingly (hence the teasing). It starts here:

http://www.mangago.me/read-manga/you_re_my_loveprize_in_viewfinder/mh/v07/c045/10/

and builds here:

http://www.mangago.me/read-manga/you_re_my_loveprize_in_viewfinder/mh/v08/c049/3/

Kuroda was next to Sudouh when Sudouh was shot, but Kuroda ran to take the bullets for Aki. Aki then refused to run and hide as directed, and instead helped Kuroda to safety. That's kind of a bonding experience, and I think the evidence that it changed their relationship somewhat is seen by the banter at the end of chapter 49.

I want to say that it's cool you have your own interpretations. I realize I post here too much because I am distracting myself from something extremely boring (and I like to talk about yaoi though most of my friends are not into it). Naturally, everyone will see things a little differently because readers are not passive--we have active minds. For example, there could be a page with two people talking. What is actually "on the page" is just a conversation and some images. However, based on context, tone and past experience, you may look at that conversation or image and infer that someone is talking as a subordinate to superior. I may look at the same page and say the interaction seems friendly, maybe even brotherly. We are both experiencing what is on the page through our own lenses of our own knowledge, experience and imagination. I admit the "brother" part is pure speculation on my part with a huge "What if" in my head, but I think the cues about the warmth and respect are there on the page, just as you think the cues of one who answers to another are there. That's cool. We just see it differently, because what is on the page is not meant to instruct or inform--it is meant to evoke. It is natural for readers to feel differently about various characters and events in a story.

I want Asami to be really a bad guy. Underworld mob boss that has a hand on everything illegal. A cold-blooded killer who will pull the trigger calmly and steadily without remorse. I want him to be everything that goes against Akihito's principles.

Then Akihito will have to question himself (again) why he's with Asami. Asami will not even try to explain himself or make excuses for what he really does for a living. Aki now will have to choose between walking in the dark path with Asami or his principles (himself).

This scene is how I envision the last chapter of this manga. I want Sensei to give it an open ending, with the readers making their own interpretation of how it will end.