Summary
Highlights
Twins were seen as a bad omen in a swordsmen clan. One twin was destined for execution due to a mark signaling weakness, leading to pity from his brother.
Everything changed when his brother defeated a master he couldn't, taking everything from him. This led to the realization that he would never shine like his brother.
Upon meeting his brother again, envy consumed him. When he developed the same mark, he discovered he would soon die. A proposal to become a demon to avoid death changed him from Michikatsu to Kokushibo.
Years later, Kokushibo found his brother, old and changed. His hatred and question of his brother's pity were cut short when his brother died naturally before the final attack.
The superiors meet, and Kokushibo arrives first. After Ubuyashiki's death, the Infinity Castle rises. Hunters appear in this labyrinth, and Kokushibo easily disarms one, recognizing him as a descendant.
Kokushibo challenges a Pillar, proclaiming his wind attacks are useless against his power. He asserts that the moon shines brighter until the sun rises, warning hunters to be more careful at night.
Kokushibo reveals he abandoned everything to surpass his brother and won't let anything eclipse the moon's bright shine. He continues to face hunters, noting that despite their efforts, no sword has reached his neck.
He observes a Demon Slayer's weapon transform like a demon's Blood Demon Art. Fear grips him, reminding him of when his brother almost killed him. Despite his body failing, he refuses to let anyone harm his master.
He questions why Yoriichi always appears, admitting he always wanted to be like his brother. He reflects on becoming a monster in vain, accepting that he will die as a demon in the darkness.
The song reiterates Kokushibo's determination for the moon to shine brighter, warning hunters of the cruel night. He emphasizes that he abandoned everything to be like, and ultimately surpass, his brother, vowing to prevent anything from eclipsing the moon's brilliance in the sky.