The Journey of Becoming A Demon Slayer

The main character ( Rem Tsubaki) will go on a dangerous journey as a demon slayer to find the demon responsible for killing her Family but is travelling with her brother which is a demon who promised to help her with her mission but later on she meets another traveler who made the same promise to find the demon who did this to her family. She does not want to trust anyone that is unknown to her so she keeps her distance, but her wish came true and she loved the boy ever since, will they get together?