The night was deep, and the guest room in the Butterfly Mansion was so quiet that only the occasional chirping of insects could be heard from outside the window.
Rin sat cross-legged on the tatami, with two blades laid flat on the floor before him.
One was the [Kusanagi Sword: Modified] that came with the system's newbie gift pack. It was pitch black, a straight-edged, single-bladed sword that was indestructible and possessed a demon-slaying trait.
The other was the [Thunder-Patterned Black-Bladed Nichirin Blade] that Haganezuka Hotaru had delivered earlier that day.
"The conductivity of the Nichirin Blade is indeed good. Tamahagane, a mineral that has absorbed sunlight, is naturally compatible with my Lightning Release Chakra."
Rin reached out and stroked the faintly flickering purple lightning patterns on the Nichirin Blade, but his brow twitched slightly. "However, the hardness is still too poor."
No matter how superb the forging techniques of this world were, the physical limits of tamahagane remained.
It might be sharp enough for an ordinary swordsman, but if Rin poured his full Chakra into techniques like Chidori Sharp Spear or a higher-level Lightning Release shape transformation, this Nichirin Blade would most likely shatter because it could not withstand the violent energy.
In a true life-and-death struggle, once a weapon breaks, even a momentary opening is enough to be fatal.
"System, can you directly integrate the material properties and conductivity of this Nichirin Blade into the Kusanagi Sword?" Rin called out to the system in his mind.
[Ding! Host's requirement detected.]
[Plan generated: Decompose the 'Thunder-Patterned Black-Bladed Nichirin Blade' (Premium Tamahagane material, high-tier Chakra conductivity) and perfectly forge it into the 'Kusanagi Sword: Modified'.]
[After fusion, the Kusanagi Sword will retain its original 'Absolute Indestructibility' attribute while gaining extreme lightning-attribute Chakra conductivity and inheriting the thunder-pattern visual effect.]
[This fusion requires 880 Dimension Points. Confirm fusion?]
"880 points? Let's round it up, huh. Confirm fusion." Rin gave the command without hesitation.
As soon as he spoke, a brilliant dark-golden light surged from the void, completely enveloping the two blades on the floor.
There was no deafening sound of hammering, nor any earth-shattering phenomenon. After only a few seconds, the dark-golden light quietly dissipated.
The Nichirin Blade that had been lying on the floor had vanished into thin air, leaving only a straight sword resting quietly in its black scabbard.
Rin reached out, gripped the hilt, and drew it with a soft clink.
The transformed Kusanagi Sword's blade remained that textured dark black, but along the edge of the blade, several winding purple lightning patterns had appeared, like blood vessels.
Just holding it in his hand, Rin felt as if the sword had become an extension of his own arm. With a single thought, the Lightning Release Chakra in his body flowed smoothly from the hilt to the tip of the blade without the slightest resistance.
"Not bad. This can even increase the power of my Lightning Release by twenty percent."
Satisfied, Rin sheathed the new Kusanagi Sword, placed it beside his pillow, and fell asleep.
...
The next morning.
The sun was bright and the breeze was gentle.
Bang! Bang! Bang!
A rough knocking on the door woke Rin from his slumber.
"Rin! Get up quickly! The sun is already high in the sky. Do you think we're going on a picnic today?!" Kocho Shinobu's crisp and somewhat impatient voice came from outside the door.
Ever since her disguise had been ruthlessly torn away by Rin a few days ago, this sharp-tongued butterfly had completely let herself go in front of him.
She had thrown her mask of a gentle older sister to the winds, replacing it with her original tsundere, sharp-tongued nature.
The sliding door was pulled open with a soft shing.
Rin walked out yawning, already changed into the brand-new black uniform of the Demon Slayer Corps.
However, he wore it very casually. The three buttons on his chest were not fastened at all, and the open collar revealed his firm collarbones. A pure black haori was draped loosely over his shoulders.
"It's so early. Are you trying to nag me to death?" Rin glanced at her.
Today, Kocho Shinobu was still wearing her iconic butterfly-patterned haori. However, perhaps because of Rin's comment yesterday about her being a short-tempered, sharp-tongued lol—ehm.. little brat, she was actually wearing a bit of light makeup today, which made her look bright and lively.
"You guy... is that how you wear the uniform? The discipline of the Demon Slayer Corps is going to be ruined by you!"
Seeing Rin's disheveled and careless appearance, Kocho Shinobu frowned. She subconsciously stepped forward, stood on her tiptoes, and reached out to help him fasten the buttons on his collar.
The distance between the two instantly closed, to the point that they could even feel each other's breath.
Rin lowered his head slightly and looked at Kocho Shinobu, who was within reach. Her plump cheeks carried a hint of a healthy blush, and her serious eyes held a trace of disdain, yet her movements were surprisingly gentle.
"The way you look now is quite like a virtuous wife seeing her husband off," Rin blurted out.
Click.
Kocho Shinobu's fingers suddenly stiffened, and a button she had just fastened was almost ripped off by her.
"You... what nonsense are you talking about!"
Kocho Shinobu jumped back two steps as if she had been electrocuted. Her originally fair cheeks instantly turned red to the roots of her ears, and her purple eyes were filled with embarrassment and panic.
"Stop flattering yourself! I'm just afraid that your thug-like appearance will make our Butterfly Mansion lose respect when you meet Oyakata-sama!"
Kocho Shinobu glared at him, trying to appear calm. She turned and left, her pace even faster than usual. "Hurry up and follow me! If you're late, I won't help you collect your corpse!"
Looking at her back as she almost fled in panic, Rin chuckled, grabbed the Kusanagi Sword from the table, and followed her leisurely.
...
Demon Slayer Corps Headquarters, Ubuyashiki Estate.
The vast Japanese-style courtyard was covered with white pebbles and surrounded by lush green pines and cypresses.
At this moment, several figures emitting powerful auras had already gathered in the center of the courtyard, either standing or sitting.
As the nine Hashira, the highest combat power of the Demon Slayer Corps, they had all arrived today for the first time in a long while.
"Hey, hey, I say, did Oyakata-sama call this special Hashira Meeting just to see a newcomer who just passed the Final Selection?"
A young man with white spiky hair and a body covered in scars leaned against a tree trunk with a face full of irritation.
Wind Hashira Sanemi Shinazugawa.
His eyes held undisguised violence. "A single person slaughtered everyone on Fujikasane Mountain? Are you kidding me! I could kill everyone in that dump for raising trash with my eyes closed!"
"Don't say that. To be able to gain Oyakata-sama's attention, this person must have extremely outstanding talent! It truly makes one's blood boil!" Flame Hashira Kyojuro Rengoku, who had yellow and red hair and bright, piercing eyes, crossed his arms and spoke loudly.