Kusui Kunato, the older sister of Hyōma Kunato and twin of Hayato Kunato, perished alongside her brother during an assault by Tenjitsu—a malevolent karakasa umbrella tsukumogami—that consumed their bodies while allowing Hyōma to flee. This tragedy became the catalyst for Hyōma’s seething hatred toward tsukumogami.

Gentle and nurturing, Kusui filled the parental void in Hyōma’s life, dedicating herself to his upbringing with unwavering care. Her compassionate presence contrasted with Hayato’s martial prowess, as he trained rigorously to hone his combat skills.

Kusui’s death anchors Hyōma’s motivations, fueling his vendetta against Tenjitsu and initial rejection of peaceful tsukumogami. Her absence strains his interactions with Botan Nagatsuki and her spirit-inhabited household, as he grapples with their harmony against his ingrained resentment.