Mafia 30. Yakuza Clans war.

Therefore, the mercenary could be Slonysh or someone from this pair. Moreover, the mercenary kills everyone first.

Yes, but I wrote earlier why it wasn't the mercenary, the ninja, or the Yakuza who killed. The murder wasn't committed with a sniper rifle.
And how does the sequence of murders affect the suspects' affiliation? All the murders occur after the blocks.