The moment the two of them infused chakra into their kunai, Minato Namikaze received the signal that the marks had been activated. He was serving as Kazemori Masaki's attendant at the time, precisely so he could send Masaki to his destination immediately.
Minato had only just turned around and had yet to speak when Masaki sensed something and walked out of the room. He looked at Minato, and a single exchange of glances was enough for him to understand.
Masaki drew a deep breath, and the chakra within him stirred. His own chakra nature blended with the chakra nature he had formed using tailed beast chakra as its foundation, producing an entirely new and powerful force.
Minato saw an intense light radiate from his teacher, carrying a heat like fire. He also had a talent for sensory ability, so he naturally understood the immense power contained within it. He felt that power could evaporate him completely.
But Masaki kept his power under control. Although Minato could sense its enormity, it remained confined within just the right range, leaving him with only a warmth against his skin, like sunlight.
"I'll go on ahead. Please call Kagami over in a moment," Masaki said.
"Yes." Minato nodded and threw three Flying Thunder God Kunai, planting them around Masaki. Since Masaki had instructed him not to follow, he could not transport him by taking him along himself. Instead, he had to use the marks on the kunai to send Masaki alone.
Masaki vanished in an instant. Minato slowly lowered his hands from their hand seals and addressed the now-empty kunai formation. "May fortune favor you in battle."
Meanwhile, Katsuya Uchiha sensed that something was wrong and prepared to attack again. Susanoo's enormous chakra hand reached forcefully toward the pair, and densely packed, distorted shadows