Being that Yuki didn't personally kill IV(4), he didn't gain any exp. Even if he wanted to gain it through exp share, that only applied in dungeons. As such, Yuki didn't gain any exp. Instead, the one that received the exp was the henchman who was forced to kill his own leader. Tears began to generate in his eyes as he couldn't believe what he had done. They weren't tears of sadness, they were tears of fear. Even if he was forced to kill one of his own, it was still a serious offence in the crime syndicate and as such, there would be punishment served which would equate to the crime he had committed.
"Well, now that this business is finished, let everyone you kidnapped go and move along. I promise you, if even a single one of you decides to open your mouths and tries to negotiate with me, I'll burn you all the ground," Yuki warned them.