After learning about the concept of "Thirteen Forms of Sun Breathing" from Chinatsu, Tanjiro hurriedly began practicing.

Although the definition of "Thirteen Forms" seems quite ordinary, it is simply the continuous use of the first twelve sword techniques.

But when facing demons, who would use fixed sword techniques in a rigid manner? The normal approach is to react to their moves and counter them. That's why Tanjiro was initially surprised when he learned about the concept of the "Thirteen Forms".

However, when Tanjiro started trying it out in the air and found that the breathing that originally felt like it was burning his body had actually become more comfortable, Tanjiro's excited appearance, which resembled that of a silly deer, made Chinatsu next to him laugh.

"What's wrong, sister?"

"It's nothing, it's nothing. I just thought of something funny. Keep practicing. But being able to use the Thirteenth Form on thin air isn't enough. The enemy won't stand still and let you cut them down." Chika said, waving her hand as she suppressed a laugh.

"Yes! I will try my best!"

Tanjiro nodded seriously, his whole body filled with fighting spirit. Even when progress was subtle, he persevered in his training, let alone now that he had found the key to make faster progress.

In the morning, Tanjiro practiced the cycle alone. Tanjiro's basic skills were already very solid, and the morning's training had already made significant progress for him.

In the afternoon, Tanjiro and Chinatsu sparred. Although their strengths were vastly different, Chinatsu could clearly feel that Tanjiro was gaining experience and growing stronger with each battle.

That night, Tanjiro and Chinatsu left the Demon Slayer Corps headquarters and headed to Tamayo's location.

Asakusa, Tokyo Prefecture.

As night fell, Tanjiro and Chinatsu once again stepped into this town, which seemed to have undergone a complete transformation.

The streets were brightly lit, with flashing lights illuminating the area, and police officers walked along the streets to ensure the safety of the people.

Here, low-level imps have virtually no chance to make a move. At least one must be an imp with Blood Demon Arts skills to survive in this town. From an imp's perspective, this town is undoubtedly a "high-level dungeon."

"Sister, I can't smell Tamayo and the others." Tanjiro sniffed hard with his nose but failed.

"They probably haven't been out much lately. It's no big deal. I remember the way," Qianxia said confidently, poking her head with one finger.

You should know that her memory is at a level that would make even Uzui Tengen exclaim "Magnificent!", so simply recalling the geographical locations she has been to is a piece of cake.

After a series of winding roads, Chinatsu and Tanjiro soon arrived at a corner where two roads led to the left and right. However, instead of going to the left or right, they chose to face the hard wall directly in front of them.

As their bodies made contact with the wall, ripples spread across it, and the two passed through the wall to Tamayo's mansion, which was hidden by an illusion.

As Chika approached the door, just as she was about to knock, a mature woman's voice came from inside the mansion.

"Come on in, the door's unlocked."

Chinatsu wasn't particularly surprised, nor was Tanjiro. However, at such close range, Tanjiro sniffed again and then, somewhat awkwardly, whispered something in Chinatsu's ear.

"Sister... Miss Tamayo seems a little angry..."

Chika's lips twitched slightly upon hearing this. She could understand why Tamayo was angry. After all, when they first met, she had said she would provide the blood of a high-ranking demon. So much time had passed. Not to mention high-ranking demons, she had already defeated so many Upper Moon demons. She should have arrived much earlier.

Fortunately, Chinatsu believed that Tamayo would be so happy to see the gift she had prepared that she would forget all her past grievances!

Chinatsu reached out and grasped the doorknob, pushing open the mansion's door. The two walked step by step down the mansion's corridor to the room where Tamayo and Yushiro were, beginning their long-awaited reunion...

After a brief chat, Chinatsu winked at Tanjiro beside her, signaling him to bring out what she had prepared.

Despite not having rehearsed beforehand, Tanjiro immediately understood what his sister meant.

It's fortunate that it was Tanjiro; if it were Inosuke who saw him winking like that, he probably would have bluntly said, "Big sister, do you have trachoma?"

Tanjiro took out a test tube containing blood from his pocket, and Tamayo, who had been somewhat alive, immediately had a gleam in her eyes.

"Could this be the blood of the Upper Moon demon?!"

"To be precise, it's the blood of Upper Moon One~"

Tamayo excitedly took the test tube containing Kokushibo's blood from Tanjiro's hand, her face showing a surprised smile that Yushiro beside her hadn't seen in many years.

Seeing Tamayo's smile, Chinatsu breathed a sigh of relief. In fact, she had almost forgotten about drawing blood from Tamayo.

In the Mugen Train arc, you can use the excuse that she fainted after defeating Akaza, but in the geisha district arc, there were plenty of opportunities to collect their blood when fighting Gyutaro and Daki.

Fortunately, she finally remembered it when fighting Kokushibo. With such high-quality experimental samples, Tamayo's research progress should be able to improve by a lot, right?

With her gaze fixed on Tamayo, who was already itching to conduct experiments, Chinatsu exhaled and announced that she and Tanjiro were about to leave.

Tamayo didn't try to stop Chinatsu from leaving, because she wanted to develop a drug that could target Muzan as quickly as possible. The drug that Tamayo developed was an extremely important factor in the fight against Muzan.

"Chika, believe me, I will succeed." Tamayo said earnestly to Chika, holding the test tube containing Kokushibo's blood.

"Haha, of course I trust Miss Tamayo, otherwise why would I give you this blood? By the way, do you want my blood?"

Chika half-jokingly pulled up her sleeve, revealing her fair arm, but Tamayo took out a blood-drawing syringe seriously.

"Yes, I'd love to! If possible, I'd like to smoke a little more!"

"Of course... no problem..."

Chinatsu looked embarrassed. Just as Tamayo was about to draw some of Chinatsu's blood for a control experiment, Tanjiro suddenly took out several test tubes containing Chinatsu's blood from his pocket.

"Um... when I was collecting Upper Moon blood, I saw so much of my sister's blood scattered around, and I thought it might come in handy, so I also collected some of her blood..."

Tamayo and Chinatsu turned to look at the several blood-filled test tubes in Tanjiro's hand, their eyes turning into beady eyes.