As for monsters...it could be tamed as long as the person's unique charm was strong enough.
After all, the monsters usually hated humans more than beasts hating humans. Thus, if the tamer's charm wasn't strong, they could fail.
For this reason, the Crimson Lily's local residents, such as the beasts and some monsters with high intelligence prepared an area for low-intelligence beasts and monsters to gather.
The area was blocked with a natural barrier created by the beasts and became a 'hunting' ground for the Crimson Lily branch guild members to tame monsters and beasts.
There were a lot of beast guardians guarding the designed hunting ground, and they would only allow guild members and relevant humans to enter.
This is definitely a good thing for both sides because the beasts also didn't really like the wild monsters that always competed for food and evolution resources.