The range of the Transparent World began to expand, and the world became clear once again. As Roa infused his magic power, time seemed to stretch endlessly.
This was the acceleration of thought.
After understanding the general function of the Transparent World, Roa decided to deactivate it.
Activating the Transparent World during battle could greatly assist him, but right now, he wished time would pass faster.
After deactivating the Transparent World, he stood up and stretched, then wandered around the mountain for a bit. Today, as expected, something unexpected happened.
To be honest, Roa thought that Muzan Kibutsuji's envoy would arrive tonight, but it turned out to be a wasted night.
Boredom aside, he still had to wait. He wasn't afraid of the enemy not coming; he was afraid they would come, and he wouldn't be there to intercept them.
If it was Muzan Kibutsuji who came, he could test the other's strength. If it was Upper Moon One, Kokushibo, he would cut off the other's head first to prevent him from causing trouble during the final battle.
Kokushibo was strong—Upper Moon One was no joke. He possessed the Transparent World and the Demon Slayer Mark, making him almost as strong as Muzan Kibutsuji.
If this guy caused even a slight disturbance, allowing Muzan to escape, Roa would be heartbroken.
Roa hadn't been in this world for long. He could stay for at most five years. If Muzan Kibutsuji tried to outlast him like he did with Yoriichi, Roa really wouldn't have a way to deal with it.
So, he had to eliminate all possible variables and deliver a fatal blow.
Ambushing was necessary. The enemy would definitely come to investigate, and he had to keep them here.
With that in mind, Roa lazily got up, yawned, and prepared to go home to sleep, planning to come back the next night to continue his vigil.
Once midnight passed, the dawn would arrive.
Roa headed down the mountain. The entire night had been boring and uneventful.
After having a meal in the town, Roa headed home, but on the way, he ran into Mitsuri Kanroji again.
The Steam Princess seemed troubled, standing in the middle of the road.
It was rare to see her, so Roa went over to greet her.
But the moment she saw Roa, she became flustered.
Roa scratched his head, giving her a curious look, and asked, "What's wrong, Mitsuri?"
Mitsuri Kanroji avoided his gaze, looking around nervously, her hands behind her back, appearing shy.
Roa could tell at a glance that Mitsuri Kanroji was hiding something in her hands, but he didn't call her out on it. Instead, he said to her, "How about coming to my place for a bite to eat?"
Mitsuri Kanroji quickly stuffed the item in her hands into her pocket, her face red as she nodded.
Roa was genuinely curious, and after a particularly boring night, he was itching for some entertainment. He couldn't help but ask, "Mitsuri, what were you doing standing there?"
Mitsuri Kanroji avoided Roa's gaze, looking down at the ground, and said with some embarrassment, "Actually, I was asking for directions to your house."
Roa scratched his head, his expression a bit puzzled.
Mitsuri Kanroji's demeanor made it clear that she had likely come to see him with a gift or something similar. Unfortunately, she had been caught off guard by Roa's sudden appearance, leaving her flustered and hastily hiding the item.
Roa was well aware of Mitsuri Kanroji's feelings for him. After all, she wasn't exactly subtle, and Roa wasn't blind. However, he knew his own situation—he would only be in this world for a maximum of five years. If he were to accept her feelings and then disappear, he would feel a sense of guilt.
As Roa was lost in thought, Mitsuri Kanroji subtly stole glances at him.
Just one look, and the Steam Princess began her usual routine.
Roa brought her to his house. Although he had told Kie Kamado that she didn't need to cook anymore, she still insisted on doing so. She said that she didn't have much else to offer, but her cooking skills were something she could contribute.
After a hearty meal with Mitsuri Kanroji, Roa felt quite satisfied.
Once Mitsuri Kanroji and Tanjiro Kamado finished eating, Roa said to Tanjiro, "Tanjiro, it's time for training."
Morning training was essential. Since Tanjiro was now here, it was better for him to become a Demon Slayer as soon as possible. The Demon Slayer Corps' entrance exam wasn't particularly difficult, and with Tanjiro's strength, he should have no trouble passing.
But becoming a Demon Slayer was just the first step. Roa's plan was for Tanjiro to become strong enough to take on Lower Moons.
After sending Tanjiro off to train, Mitsuri Kanroji looked at Roa with pleading eyes.
Her expression made Roa feel a bit awkward, and he finally sighed, "Mitsuri, is there something you need?"
This time, she didn't shy away. Instead, she looked at him seriously and said, "Roa, can you come outside for a moment?"
Roa scratched his head, already having a rough idea of what she wanted to say.
He also mentally debated whether he should accept her feelings.
In the end, he shook his head, feeling a bit self-deprecating for being too kind-hearted and not wanting to deceive her.
Roa followed Mitsuri Kanroji outside, standing under a tree in front of the house. Tanjiro Kamado, who was outside, gave them a curious look but eventually turned his attention back to his sword.
Time had flown by, and it was already summer. The scorching sun and the changing seasons gave Roa a sense of disorientation.
He looked up at Mitsuri Kanroji, who was no longer wearing her loose pink kimono. Instead, she was dressed in the Demon Slayer Corps uniform, which clung tightly to her chest, accentuating her figure.
Mitsuri Kanroji reached into her pocket to pull out a small object made of red string. Her mother had taught her how to make it when she was young, telling her that if she gave it to a boy she liked and confessed her feelings, and if he didn't reject her, they would be together forever.
But before she could take it out, Roa shook his head with a smile.
Mitsuri Kanroji's expression froze for a moment. Although she was a bit of a romantic, she quickly understood what Roa meant.
In an instant, her shyness faded away.
She looked up at Roa and asked dejectedly, "How did you know?"
Her first thought wasn't why she had been rejected, but how Roa had figured it out.
The girl's thought process was a bit unusual. Roa sighed and said, "It was kind of obvious."
Mitsuri Kanroji hung her head in disappointment. "Was it that obvious? I thought I hid it pretty well. So, can you tell me why? Is it because of my hair color? Or is it because, like they say, I eat too much and have too much strength?"
Roa smiled and reached out to pat Mitsuri Kanroji's head. "I've told you before, there's no need to be afraid of your own talents. They're gifts from heaven. You'll eventually meet someone who loves you for who you are. Besides, I've always seen you as a little sister. That's all."
Even though she was probably older than him.
Mitsuri Kanroji sighed, but Roa's meaning was clear. She could only nod in resignation.
It was natural to feel disappointed. Anyone would be after being rejected.
It took a lot of courage to confess, and being rejected would naturally leave anyone feeling down for a while.
Roa was also a bit troubled. Attraction often depended on first impressions, and Roa's appearance was the kind that could make a strong first impression. With that kind of advantage, almost anything he did would have a special impact. Combined with Mitsuri Kanroji's romantic nature, it was no surprise she had developed feelings for him.
Unfortunately, while Mitsuri Kanroji had fallen for Roa, Roa's first impression of her, while positive, wasn't enough to lead to marriage.
If it were just a physical relationship, it might have been possible, but Mitsuri Kanroji was a pure-hearted girl with a beautiful vision of love. If Roa were to take advantage of that, he wouldn't be able to live with himself.
Roa tried to comfort her, but to his surprise, Mitsuri Kanroji wasn't as heartbroken as he had expected. The Steam Princess had a good ability to manage her emotions, and after a while, she was back to her cheerful self.
Her resilience left Roa a bit speechless, but it also showed that she had a strong ability to bounce back.
As he was seeing her off, Mitsuri Kanroji suddenly turned around and bowed deeply to Roa. "Thank you for always taking care of me. To be honest, I've been asking myself a question: Would a girl like me, with my strange hair color and all, be rejected by someone as handsome and strong as you? I'm not an outstanding girl. I'm not as gentle and kind as Nezuko, nor do I have a particularly beautiful appearance. Even my hair color is strange."
Roa opened his mouth to offer more words of comfort, but Mitsuri Kanroji cut him off.
She still wore a faint smile, her light green eyes slightly narrowed as she said, "To be honest, I'm not even sure why I wanted to confess to you. Maybe it was a mix of admiration and other feelings. Someone as kind and gentle as you is bound to be popular with girls. Even your rejection was very gentle. In any case, thank you for always encouraging me. Since joining the Demon Slayer Corps, I've been doing well, and I've gained everyone's recognition. Even though I'm a bit sad about being rejected, I'll keep working hard!"
Just when Roa thought she was giving up, she mustered her courage and added, "I'll make you like me!"
Roa: ???
Roa was momentarily stunned by her radiant determination, unsure of how to respond.
And was he really that great? Her compliments were making him blush.
Well, he'd just have to see how things played out. If she still felt the same way in the end, he'd figure out a way to handle it properly.
There's an old saying in China: "If you're not going to marry her, why lead her on?" But Roa's previous actions had been a bit ambiguous, and the current situation was largely his fault.
Sigh.
He'd just have to take it one step at a time. If all else failed, maybe he could take Mitsuri Kanroji with him when he left this world.
In the end, Roa chose to smile at her.
Mitsuri Kanroji waved goodbye with a smile, and the matter was settled for now.
Roa sighed helplessly, watching her leave before heading back inside.
Now it was time to train Tanjiro Kamado.
Since the courtyard wasn't very large, Roa decided to continue the training at Kyojuro Rengoku's house. After all, he had paid enough for the privilege, so he might as well make use of it.
When they arrived at Kyojuro's house, they were surprised to find him sitting at home.
Kyojuro noticed Roa and immediately broke into a bright smile, calling out, "Handsome young man, over here!"
As Roa entered the courtyard, Kyojuro asked, "Would you like something to eat?"
Roa shook his head. "We just ate. We're here to train Tanjiro. Oh, by the way, Mitsuri Kanroji just had a meal with me."
Tanjiro Kamado's expression turned a bit strange. Although his hearing wasn't particularly sharp, his sense of smell was exceptional, allowing him to easily discern others' emotions.
As Tanjiro's understanding of the Sun Breathing technique deepened, his ability to sense emotions also improved.
For a moment, he had clearly detected a sense of loss in Mitsuri Kanroji, though it had quickly faded.
Combining their earlier conversation and their previous interactions, it wasn't hard to guess what had happened between them.
Kyojuro nodded. "She just ran off with a wooden sword, probably to practice. She should be back soon."
Roa nodded, and Kyojuro didn't dwell on the topic of Mitsuri Kanroji. Instead, he fixed his intense gaze on Roa and asked, "Do you have any methods to help me get stronger quickly?"
Roa raised an eyebrow. The quickest way to gain strength was through the Demon Slayer Mark, but those who awakened it rarely lived past 27. While the Mark could significantly boost one's combat abilities, Roa wasn't planning to suggest it. That left the Transparent World, the Crimson Red Nichirin Sword, or the Sun Breathing technique.
The Transparent World was something one had to comprehend on their own—it could take a moment or a lifetime. While Roa could help increase the chances of awakening it, it wasn't a quick solution.
As for the Sun Breathing technique, while Roa was willing to teach it, whether Kyojuro could master it was another matter.
In the era of Yoriichi Tsugikuni, there were undoubtedly other geniuses, but even Yoriichi, who lived to an old age, never found a successor to pass on the Sun Breathing technique.
That left the Crimson Red Nichirin Sword.
Based on Roa's analysis, the Crimson Red Nichirin Sword was likely formed through extreme heat. When the sword's temperature reached a certain point, it would turn crimson.
But this was just speculation. Roa's own Nichirin Sword hadn't reached that level yet.
Thinking about it now wouldn't help, so Roa decided to try teaching Kyojuro the Sun Breathing technique.
Roa said to Kyojuro, "Alright, let's start training."
Kyojuro stood up, grabbed two wooden swords from a nearby rack, and tossed one to Roa.
Roa began teaching Kyojuro the Sun Breathing technique.
Unfortunately, as expected, things didn't go smoothly. The Sun Breathing technique was something only Tanjiro Kamado could barely use. For Kyojuro, it was too demanding.
It wasn't that Kyojuro's physique was lacking—it was simply a matter of compatibility.
The Flame Breathing technique was a simplified version of the Sun Breathing technique. While it removed many elements, it also significantly reduced the strain on the user. The full Sun Breathing technique was extremely taxing.
In theory, Kyojuro should have been the most suitable candidate for the Sun Breathing technique after Tanjiro. However, even if he could use it, he would likely experience a period of exhaustion afterward, making it less sustainable than the Flame Breathing technique.
In the end, Roa could only shake his head in resignation. He then looked at Kyojuro and said after some thought, "I do have a method that could make you much stronger, but the cost is too high. I'm not ready to share it yet."
Kyojuro was momentarily stunned, his expression thoughtful. To Roa's surprise, Kyojuro didn't press further. He simply nodded and dropped the subject.
Kyojuro's straightforwardness left Roa feeling a bit awkward, but he was doing it for Kyojuro's own good. With two Upper Moons already defeated, if Roa could take down Upper Moon One, Kokushibo, that would leave only three Upper Moons. Roa could then attempt to solo Muzan Kibutsuji, leaving the remaining Upper Moons for the Hashira to handle.
That way, no one would die, and a happy ending would be achieved.
Well, that was the plan, at least.
Of course, this all hinged on Roa successfully defeating Kokushibo. If he failed, everything would be for nothing.
Since the Sun Breathing technique wasn't working, Roa could only focus on refining Kyojuro's swordsmanship.
Roa activated the Transparent World, and in an instant, all of Kyojuro's movements slowed down. Roa began pointing out the flaws in Kyojuro's technique.
At the level of a Hashira, swordsmanship was already highly refined. It wasn't so much about mistakes as it was about openings in their attacks.