Inugami beheads him in front of Ririchiyo in chapter 18 during the Demon Raid.
-Second arc- 23 years later He is 21 years old. Has no memories of his past life except for the vision of a girl with dark hair that constantly appears in his mind whenever he notices anyone with dark hair. However, even though he does not have any memories of his past self, he does know about Ririchiyo due to the previous Soushi placing all the pictures, letters, and anything related to Ririchiyo in a disk he found.
He falls in love with Ririchiyo and grows insanely jealous of his past self due to Ririchiyo choosing him over this Soushi.
Due to his past being dramatically changed-Ayame (Kagerou’s mother) saves him earlier from his house arrest after being advised by the previous Ririchiyo-, Soushi does not learn the feelings of shame, guilt, trauma, or gain any experience in treating other women with care. The current Soushi is more pure than the previous Soushi, but he is more brutal, naive, introvert, distant, and clingy than the original Soushi.
When deciding to write letters to the past to prevent tragedy from happening again, Soushi only writes the letter to previous Soushi using Ririchiyo’s words. He wants to help Ririchiyo save the previous Soushi because the current Ririchiyo rejected the current Soushi because she can only love the past Soushi.