Arit knew that dealing with the Russians in the tournament might be the best way to reduce casualties as much as possible.
Luna also sighed as she saw the sense in Mark's suggestion. Luna didn't like the fact that they were just going to allow the anima to continue whatever it was that they were planning, but Luna knew that it would be stupid to say anything about it now instead of waiting for a better time. And besides, Luna was more than aware of the fact that the Japanese government didn't like them at all. If Mark said something now, then it was more likely that they would ignore him just because they didn't like him. And if they listened to him and tried to attack the monster, then too many lives would be lost in the process.
Waiting until they were on an island where only superhumans were present was the ideal situation.
Luna asked another question.