I think that Utsukushii Tenshi to Eien no Akuma means "Eternal Devil and a Beautiful Angel in English", but I'm not sure, so don't count on it. Maybe you might have to ask someone else to be for sure. I'm not Japanese, so I don't know if this is correct or not.
English spelling: Akuma Japanese spelling: 悪魔
devil, demon, fiend, Satan, evil spirit
nani okottemo aishiteru
it means "i love you"
devil in is akuma de unless you mean inn
Demon as in "devil" is "akuma." Demon as in "evil spirit" is "youkai."
オオカミの悪魔 Ookami no akuma
demon blade in Japanese is akuma no tsubasa
"Aishiteru" means "I love you" in Japanese, but it's only really used unless you're absolutely serious about the relationship.If you're not sure whether you are dedicated yet, you can say "Daisuki" instead, which means "I really like you". It's more relaxed, for example, if you're just starting a relationship with someone.
Hi no akuma
"aoi akuma"
Furasshu no akuma