Shitara is a musician in Kyūma rock band. Shitara has a generally calm and easy-going nature and is possibly the next most intelligent member in his team next to Kyūma. He also seemed to express the greatest level of understanding of Kyūma's thoughts and habits in his team.
Five months before Arisu's arrival. Sōgo cleared the Three of Spades on the first day with the rest of the band. Following the end of the second stage. He, alongside the rest of the group, decided to stay in the Borderland as citizens.