On the fifth day, Oborozuki received a letter from the Demon Slayer Corps — or rather, every swordsman in the Demon Slayer Corps received the same letter.
It wasn't an evaluation of Yoriichi's actions. It was a notice of a demon attack on the Corps' headquarters.
Hordes of demons had broken into headquarters, slaughtering countless Kakushi and regular swordsmen... They had even killed the current Master.
Although the surviving swordsmen escaped with the Master's wife and the young heir, the Demon Slayer Corps would be unable to function normally for the time being.
"How could this happen..." Oborozuki read to the end of the letter, disbelief nearly overflowing from his eyes.
Yato stormed upstairs after finishing the letter, found Yoriichi, and slammed the paper into his arms with a savage look.
"Read it!"
Yoriichi, who had never joined the Demon Slayer Corps, had not received the letter. He opened it in silence; his brow tightened more and more as he read, until he reached the final line—
[The leader of the demons has been identified as the former demon-slaying swordsman Tsugikuni Michikatsu. This individual possesses formidable strength. Should you encounter him, all non-Class A swordsmen must retreat immediately.]
When Yoriichi read that, he felt as if all the blood in his body froze.
[What?]
[Is this true?]
[But why...]
The paper slipped to the floor. Yoriichi's usually steady hands trembled — this was the third time.
This was the third time he'd felt completely at a loss. The first had been when he discovered his beloved wife Uta cruelly killed by a demon. The second was after enduring hardship to arrive, only to find Hiru had become a demon that could not see the light of day. And now — this was the third time.
...
"Brother?" Hiru appeared at the doorway, face pale, eyes unsettled as he looked at Yoriichi. "Did something happen?"
Oborozuki, who had followed, handed the letter to Hiru; his voice was unusually cold.
"Read it yourself."
Hiru took the paper, scanned it, and his expression dimmed.
"Looks like he's accepted being a demon..."
"So demons can't be trusted at all! After all, you two are brothers — you're the same kind of scum!" Yato glared at Hiru. "You wanted another test, didn't you? Fine — let's go!"
Before Yato finished speaking he cut his own arm; bright red blood welled out.
This time Hiru's pupils only shifted from ink-black to gray and contracted for a moment before returning to their octagonal shape.
"I still want to eat — but sorry, I've managed to restrain myself. Or rather, I've sealed my appetite."
"Sealed?" Oborozuki hurried to Yato's side to bind the wound after confirming Hiru had genuinely restrained himself; his hostility eased a little. "Explain."
"Alright." Hiru nodded. "Mr. Oborozuki, you should remember my first test. If my brother's crimson blade hadn't snapped me back to my senses, I would have bitten. Pulling away from you, Yato-san, then, nearly drained everything of my will."
"So you weren't in control then," Yato said coldly. "You really wanted to kill me."
"Yes." Hiru didn't hide it. "But at that time I painted a picture. It sounds impossible, but I put my murderous intent into the painting. I kept the memory, but that intense, feeding-driven desire — the urge to kill that came with eating — faded. Over the past days I studied this ability, and last night I succeeded in painting my desire to [cannibalize]."
"So you still feel hunger, but you won't be driven by the demon instinct because you've lost the desire to feed?" Yoriichi stepped forward calmly, as if unaffected by the earlier scene. "Well done, Hiru."
"Not entirely." Hiru shook his head; he could sense the mingled sorrow and relief in Yoriichi. "The painting's preservation is temporary. When it decays, the desire will return. Emotions leak back as the painting deteriorates, coming back into my body. It's only a stopgap. This is probably a use of Blood Demon Art, but I haven't fully worked out the timing. Maybe, once I understand it better, I can detach it from a physical object and truly seal my cravings for devouring and slaughter."
Yato snorted in displeasure. "Hmph. What a pity."
Whether he regretted Hiru hadn't fully mastered himself or regretted missing a chance to kill him was unclear.
"I'll accept you for now." Oborozuki took back his letter from Hiru with a sad look. "Mr. Hiru, you're really trying to hold to your limits. It would be cruel to dismiss you entirely because of my prejudice... Mr. Yoriichi, what are your plans? Will you stay here, or...?"
"I'm going to find the Demon King." Yoriichi unconsciously touched the short flute in his chest. "I'll slay him and end this tragic cycle. If Heaven gave me this strength, it's so I could do exactly that."
"...Then please avoid other Demon Slayers if you can. Even though I know it wasn't your fault, just thinking about it makes me furious." Oborozuki's eyes reddened; he looked like he might cry, his voice full of hatred. "Our Master was gentle and forgiving — he didn't deserve such a ridiculous betrayal! A Demon Swordsman turning demon is absurd enough, but to lead demons in an attack on headquarters — unforgivable! That creature — no, that demon — should die with its head severed!"
Yato, realizing he'd vented his anger, quickly apologized to Yoriichi and Hiru.
"I'm sorry, Mr. Yoriichi, Mr. Hiru. I let my rage get the better of me. But if I meet that demon, I'll make sure he dies in agony. He doesn't deserve to live."
"No, it's fine. His choice to become a demon may be tied to me." Yoriichi's gaze dimmed as he bowed to them. "It's presumptuous, but if you get any information, please tell me."
Yato only snorted in response.
Oborozuki took several deep breaths to steady himself and moved on to another concern.
"If you're going to hunt demons, Mr. Yoriichi, shouldn't you bring Mr. Hiru with you?"
"Yes. I won't let him out of my sight. I'll watch him closely." Yoriichi looked at the pale Hiru and gently ruffled his hair. "You've worked hard to get this far, Hiru."
"Compared to the burden my brother bears, it's nothing." Hiru shook his head. "Without him, I might already be a man-eating demon."
"Then what will you do?" Oborozuki looked at Hiru. "You can't go out in sunlight, right?"
"True. If we only traveled at night, my brother and I would be too conspicuous. And if my brother carried a box..." Hiru gave a bitter smile. "A swordsman with a coffin would be even more noticeable."
"Demons can change shape, right?" Yato put his hands on his hips. "Why don't you shrink down and follow your brother?"
"Shrink?" Hiru frowned slowly. "I'll try..."
Hiru concentrated and shrank himself. Bones creaked, muscles tightened, and his fitted clothes went baggy. Standing beside the now-taller three, he tugged at the too-large garments; his voice turned childish.
"I could get smaller, but then the clothes would be really inconvenient..."
"Remember when you first came to the Tsugikuni family? You were about this size..." Yoriichi let a faint smile show. "If the box's size is like that, it could pass as luggage."
Hiru struggled to gather his clothes and looked up. "So I change back now?"
"Mm."
...
Reverting brought an awkward problem. His shirt was only a little tousled — no big deal — but his pants... clearly, at his original 1.8 meters, a three-year-old version of himself couldn't keep them up.
Even holding them with his hands during the change only helped halfway; now the pants hung half on. If it weren't for the length of his top, Hiru would have wanted to bury himself out of shame.
"Clothes are a serious problem..." Yoriichi considered, eyes serious, thinking through how to spare his brother from such embarrassment — even contemplating learning to tailor.
"Indeed. Demons can change size, but clothes aren't part of them." Yato inspected Hiru. "If his pants fall down every time he opens the box, that's too..."
"Ahem." Oborozuki glanced at Hiru, whose face was beet-red. "Let's leave him to have some space and time. I think he'd prefer to be alone right now."