Necessity.

'Master, I, the great demon Bear, am back!' The bushes to Cain's left squirmed before the huge figure of Ruby was revealed to him.

Ruby, who had served as diversion had made her appearance after she had led some of the devils away. Cain had communicated to her the distance, as well as the exact time she could kill her pursuant.

As Ruby was a very strong mutant beast with the ability to create her skills, she was able to easily accomplish this task.

Within the effective range of {Seal}, they could kill as many devils as they wanted without alerting the enemy as long as it was done in the time frame of a second.

However, with their incredible speeds, the number of things that could be done in under a second was a plethora...

Staring at the huge mutant bear, Cain couldn't help but wonder...

"How do you know what you are, Ruby?" Cain asked.