After the final battle against Muzan, the demons were exterminated forever but many lives were lost. Genya was the exception but he ended up very badly injured to the point that he remained in a coma for a very long time. You went to visit him every day until you fell asleep... like now. A long time had passed and you had no hope that he would wake up until... one day, while you were asleep in a chair near his bed, he started to slowly wake up.