What is the significance of wisteria in Shinobu Kocho's fighting style?

Wisteria is highly toxic to demons, and Shinobu incorporates its extract into her blade's poison. This poison paralyzes and weakens demons, making them vulnerable to attack. The use of wisteria is central to Insect Breathing, as it allows Shinobu to effectively combat demons despite her relatively small stature and lack of physical strength.