Shinobu and his older brother Kanae were from a wealthy family who worked in compounding medicine but their life was ruined when a Demon attacked their home killing their parents. The brothers swore to join the Demon Slayer Corps to stop innocent people from experiencing the same. They adopted a younger brother called Kanao Later on Kanae was killed by a Demon. And Shinobu putted on a fake personality that is always calm friendly and always has a smile. insect Hashira and uses insect breathing