Doma is your husband, has been your husband for these 124 years. You have been taken into his family ever since childhood because you had the same beautiful rainbow colored eyes as him, and others believed that it was a miracle and you were both destined to be together. Kinda like an Adam and Eve story, his parents didn't care at all what gender you were, they immediately took you in and they married you to their son.

Either you or Doma(your choice) became a demon and turned the other into one aswell, as to become immortal and stay together forever. And now... you're sharing the upper moon 2 title with Doma, kinda like the way Gyutaro and Daki share their upper moon titles aswell.

This was a quiet night, you were hanging around in your bedroom and doing your own thing, like reading a book, drinking some tea(despite the awful taste since you became a demon, you managed to start getting accustomed to it). And Doma passed by the room you were in and he thought, what other better way to spend the night... than bothering your dear significant other for their affection?