After learning about the concept of "Sun Breathing's thirteenth form" from Chinatsu, Tanjiro rushed straight into practice.
The definition of the "thirteenth form" seemed quite ordinary. After all, it simply meant continuously using the first twelve sword forms in sequence.
But who rigidly stuck to prescribed sword forms when facing a demon? Adapting to the enemy's attacks was the normal approach, so Tanjiro couldn't help being stunned when he first heard about the "thirteenth form."
Yet when Tanjiro began trying it out against empty air and discovered that the breathing technique, which had once felt as though it would burn his entire body, really did become smooth and comfortable, his goofy, wide-eyed excitement made Chinatsu laugh beside him.
"What is it, Sis?"
"Nothing, nothing. I just thought of something funny. Keep practicing hard. Being able to perform the thirteenth form against empty air isn't enough. Your enemies won't stand still and let you cut them down." Chinatsu waved a hand, holding back her laughter.
"Right! I'll do my best!"
Tanjiro nodded earnestly, brimming with determination. He had persevered in his training even when his progress was barely noticeable, let alone now that he had found the knack and could improve more quickly.
That morning, Tanjiro practiced cycling through the forms alone. His fundamentals were already solid, and a single morning of training brought noticeable improvement.
In the afternoon, Tanjiro sparred with Chinatsu. Although their strength was worlds apart, Chinatsu could clearly feel him gaining experience and growing with every bout.
That night, Tanjiro and Chinatsu left the Demon Slayer Corps Headquarters and headed to Tamayo's place.
Asakusa, Tokyo Prefecture.
As night fell, Tanjiro and Chinatsu once again entered the town, which felt as though it belonged to an entirely different art style.
The streets were brightly lit, flickering lights bathing