
"Im gona punish( ) this month and make Him clean that damm back seat." insert name of who ever pissed him off that day.

"Lucky bastard."

look at the bottom left, there is a divider in the car , you can close or open it
http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/mh/v06/c032/22/

Yep. And he sees Asami throw Aki in (when Aki has clothes in place):
http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/mh/v000/c001.1/13/
and then they come out like this:
http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/mh/v000/c001.1/18/

I think Kirishima can't see what is happening behind him, but he had guessed everything and doesn't really care as long as he knows that Asami is safe. He's always impassive (except when he thinks that someone is bothering his boss, like Akihito sometimes^^) but he's always attentive to Asami's needs.
What Kirishima wants is Asami's safety and happiness. I think he likes (worships?) and deeply respect Asami so, as long as Asami is happy and satisfied, he doesn't care what or who is satisfying him.
So, in my opinion, his thoughts must be something like that: "Ah, I'm glad because Asami-sama is going to enjoy his night and will be satisfied and rested in the morning. He deserves it because he works so hard and so much! I told him to take a holiday but he doesn't listen. And I hope Akihito Takaba, this brat, isn't going to bother Asami-sama with his impertinence."
What do you guys think is going through Kirishima's head when he is driving and Asami is molesting Aki in the back seat?