So you’re in the mood for a good old-fashioned shounen story about fighting monsters with magic, but every time you watch Twin Star Exorcists you wish someone would slap some common sense and courtesy into the characters? You are in luck: Shounen Onmyouji is available on YouTube, albeit as an old fansub tranlating the dialogue into something similar to, but not quite that same as, English. (It’s intelligible; you just occasionally need to translate the translation. (Update: The second episode and beyond use a much more readable translation.))
Shounen Onmyouji was one of the last series licensed for North America by Geneon, just before it ceased its American operations, and consequently most of it is difficult to impossible to find legally at reasonable prices. Someday someone will rescue the license — it’s too good a show to remain forgotten — but who knows when?