Alrighty then.
The riddle: I am a builder, yet I'm unlike you. I am... Beaver
I think if I add more clues i would be simple... A, B and R were found out by LioNeeZ.
Hinode gave the correct answer.
Could you please reupload these?
https://www.anime-sharing.com/threads/2003-witch-fake(フェイク)-soundtrack-op.1217706/
https://www.anime-sharing.com/threads/2000-pinpai-rebirth(リバース).1314894/
https://www.anime-sharing.com/threads/1998-pinpai-missing-itsuka-kitto-(missing-~いつかきっと~)-soundtrack-op.1210849/ https://www.anime-sharing.com/threads/2002-witch-milkyway-2-cd-soundtrack-op-ed.1431041/