I'm having a little throwback with my childhood anime today. The following anime might not be as popular as they were back in the days but the soundtrack is still amazing!
Song: BoA - Every Heart
Song: Ayumi Hamasaki - "Dearest"
Song: Aqua Timez - Alones
Anime: Fullmetal Alchemist
Song: Yui - Again
Okay, to be fair this one is not that old but Yui's voice is amazing!