Alluring Secret Black Oath

Summary:
Once upon a time there was an angel in love with the world. And one day he came to the world ready to sin, but he did not know that his true love was waiting for him.

Notes:
Note: This one-shot is XiaoVen adaptation of Kagamine Rin/Len's Alluring Secret song
Song: Kagamine Rin/Len's Alluring Secret Lyrics by: Line
https://www.youtube.com/watch?v=0-BJk7Q5-iA
English is not my main language so I am sorry for my mistakes