It's from a manga called Demon spirit seed, sorry I forgot the chapter number but it was one of the cover pages
It wasn't her voice she traded away but her emotions. AND IF ANYONE READING THIS HASN'T WATCHED HENTAI OUJI STOP READING NOW, SPOILERS COMING! She doesn't get her emotions back though, but she learns to live without them.
Thank you, I watched the anime but it only had 1 season, will take a look at the manga or light novel if it has one
I had my exams too recently but I'm Always reading novels only last minute revision, I think I did well on them