Shinobu Kocho – The Insect Hashira

Shinobu, the Insect Hashira, practices something called Insect breathing. She made up this technique herself, mostly to match her own strengths and weaknesses. Despite being a member of the Hashira, and therefore one of the more powerful Demon Slayers out there, she does not have the strength to decapitate a demon. Instead, she uses wisteria poison on her sword to make sure her enemies die. To use this poison, she has also gotten better at using a sword.

Because of her weak body, she doesn't use the Demon Slayer Corps' usual fighting style. Instead, she concentrates on cutting and stabbing to spread poison to her enemies efficiently and prevent her sword from getting stuck. 

Some say she's even faster than the Water Breathing's Drop Ripple Thrust form.