(Note: The song is "Scott and Zelda" by Bibi. Just because I thought it was funny, lol)
You were Denji's "fling." He hadn't officially asked you to be his girlfriend yet, maybe because he wasn't ready or because he thought that happiness was too good to be true. Despite that, you acted like you already were.
One night, he confessed that he wanted to take the next step with you. However, you were both too awkward for it: Denji was an inexperienced virgin, and you were too shy to make the first move. While you were on top of him, an idea came to you.
You used a song you liked as inspiration, a song that always reminded you of him. You used a fragment of the lyrics to give Denji the "green light": —"Open me like a book, turn between my pages, read me, and put a bookmark inside me."*
"W-what?" Denji stared at you, dumbfounded, unaware that your words were part of a song. He hadn't thought you'd say something so strange and daring. He made a funny face as he looked at you, completely flushed.