Not intended

pic creds to @M8RegT9DxEdzkA1 on twitter :')

Once you die you get a choice. Live another life or work for the heavens. If one chooses to live another life, you can choose if you want the same soulmate you had, or change them into the next person the heavens deem fit. There are, however, some people in exception to this rule. Some people are not assigned a soulmate.
Atsumu, a commoner is ruled under Sakusa Kiyoomi, the king. They were never supposed to meet. So what happens when they do? It's not what the heavens intended.