If you asked what the difference was between Shisui training Total Concentration Breathing and ordinary breathing, ordinary breathing was like eating bite by bite to gain sustained strength, while Total Concentration Breathing was like suddenly taking a huge bite in the middle of a meal for a brief burst of power.
The difference was that training Total Concentration Breathing was far harder than simply taking a big bite of food. Taking a big bite only required opening your mouth wide and controlling your mouth muscles, whereas Total Concentration Breathing was not as simple as opening your mouth and inhaling deeply.
Training Total Concentration Breathing was somewhat like sprint training, gradually building explosive power bit by bit.
When Shisui had first learned it, he had not felt any difference from usual. He tried hard to concentrate his breathing more and more, but nothing changed much.
That did not change until the fifth day.
"Flame Breathing: Total Concentration Breathing, Phoenix Flower Claw Crimson!"
Shisui held four kunai between the fingers of his right hand as Chakra gathered in his palm. In an instant, all four kunai were engulfed in flames, and Shisui swiftly launched them.
Boom! Boom!
The fiercely burning kunai were like tiny fireballs. They exploded upon striking the ground, blasting out small craters.
"Releasing without hand seals? How did you do that, Shisui?" Obito could not help asking curiously.
Obito had once gathered flames directly in his palm to attack Might Guy during the Practical Exam. Strictly speaking, that could barely count as a seal-less Ninjutsu since it had involved Chakra Nature Transformation.
But in reality, Obito's was merely an ordinary Nature Transformation technique. The flames were just ordinary flames without any additional effects, and he could not increase their power by adding more Chakra because that would easily burn