i think kuze was mad bc shimijou(?) was thinking of blowing out the rest of the yakuza group, the chapter where kuze and his partner was tied up and the police suddenly barge in means it was all planned and shimijou sacrificed himself as the bait since not all people from the yakuza knows him (they did not know that he was the one who made the yakuza leader get caught) so he was able to lure out the rest of the gang.
shimijou pretended to caught the two police who were investigating him, but the truth is, him and kuze was planning it all along.
other than that, kuze was mad at shimijou because at first, he doesn't agree with shimijou's life because that plan means shimijou's life will be at stake. it was a plan only the two of them knows (tho kuze's partner seems to have a gist of it) which means shimijou will not be protected by the police and might get killed. but all's well that ends well, they both got back safe and sound.
i'm confused with the last ch, Kuze was mad because the uke was gonna go back to japan so.... did he? Or did he not? Or this is related with the ch where Kuze appears after two months because he took the place of the uke and he was the one to go back? i'm so lost