After resolving Nezuko's situation, Tanjiro and his companions decided to take some time to recover and undergo new, specialized training under the Demon Slayer Corps.
Ren Kuroda, however, returned to the main world with the Spider Princess. Though he had spent nearly two years in the Demon Slayer world, the time difference calculated at a 100:1 ratio meant only about a week had passed in his own world.
"Hey, where did this beautiful lady come from? Wearing a kimono like that so late at night—are you a hostess at one of the geisha houses nearby?"
As Ren and the Spider Princess stepped out of a narrow alley, they ran into a middle-aged office worker, completely drunk and leaning against the alley entrance. His gaze lingered far too long on the Spider Princess, whose beauty and alluring figure were impossible to ignore—even for a drunken man.
Seeing him approach, Spider Princess's expression twisted with disgust.
"Lord Ren… may I kill him?"
Ren, accustomed to her dark humor, couldn't tell if she was serious. A single nod from him, and the man would almost certainly end up dead in the street. The Spider Princess, whether demon or monster, had never held human life in high regard.
"Little beauty, you're wild, but I like that. Your… sounds will be even more captivating later."
The man smirked and reached out toward her, clearly thinking she was joking. But before he could succeed, Ren acted. In a blur of motion, he snapped the man's outstretched arm with one hand and slammed the back of his neck with the other, sending him sprawling.
"This world is different from your last one," Ren explained to the Spider Princess. "Don't kill people indiscriminately unless it's a special situation. The technology here is advanced. If you go around killing someone, it'll cause a lot of problems. In those cases, just teach them a lesson—and leave it at that."
By the time the man woke up, he would probably only remember trying to act like a scoundrel, running into a formidable opponent, and getting swiftly taken down.
For Spider Princess, the modern world felt uncomfortable at first. In the Demon Slayer world, people and technology were simpler, more like an ancient society. Ren patiently explained the basics while leading her toward home.
The small rented house that had once sufficed for the two of them and the Nurikabe was now a bit cramped with the addition of Spider Princess.
"If you don't get out of here, I'm calling the police! How many times do I have to tell you? Yuto isn't joining your 'Unnatural Countermeasures Group'! He's still a student—so however many times you come, it's useless!"
Ren, though only recently returned, still remembered the way home well. But as they approached the door, he froze at the scene before him.
His mother, Tenjōin Masami, no longer timid as she had once been, was wielding a broom with fierce determination. And the man she was chasing away was unmistakable: Kamishiro Isshin, the persistent Onmyoji recruiter who had tried multiple times to draw Ren into the so-called Unnatural Countermeasures Group.
"Mrs. Tenjōin, please calm down! I understand you want a quiet life for your son and don't want him involved with the Onmyoji family affairs. But he's an exceptionally talented prospect! To bury that talent would be a complete waste…"
A cigarette dangled from Kamishiro Isshin's mouth as he spoke, but before he could finish, Tenjōin Masami smeared his face with her broom.
Isshin had arrived at Ren's home the day after he returned, fully briefed on his extraordinary potential and status as a fallen Onmyoji disciple. Everything seemed to be going according to his plan. He quickly gathered information and attempted yet another round of persuasion.
He had assumed the main obstacle was Ren's own will. Surely, he thought, the rest of the family—aside from Ren's younger sister—would help convince him. After all, Tenjōin Masami, born into a prestigious Onmyoji lineage, would surely want to revive the family's reputation.
Isshin's calculations, however, were dead wrong. Tenjōin Masami had no interest in cooperating. Upon learning he came from the Unnatural Countermeasures Team, a government organization specializing in yokai eradication, she immediately chased him away—broom in hand.
Despite being from an Onmyoji family, Masami lacked the "family honor" sense Isshin expected. Even after being expelled, Isshin persisted, reporting back daily without fail.
At first, she ignored him, but eventually her patience broke. She physically assaulted the shameless recruiter, leaving no doubt: under no circumstances would Ren join the Unnatural Countermeasures Team.
Who better than a mother to know her child? She understood exactly what kind of danger awaited him in a group tasked with killing demons. Ren, a half-demon himself, would be walking straight into an enemy camp. No negotiation was possible.
Tenjōin Masami had made her stance crystal clear: Ren's involvement with the Unnatural Countermeasures Team was completely out of the question.