I wondered, for a while, why Devilman had never had a fully accurate adaptation. There was the original show, that essentially had nothing to do with the manga because it was produced early in the manga's run and had to make up its own material. The OVA was fairly accurate, but it stopped at the fight with Sirene. Crybaby hit many of the manga's beats, but ultimately updated many aspects and changed many others. And then I read Devilman, and I understood. Such a seminal work, one that inspired so many other, whose influence can still be felt to this day, is quite flawed. Devilman has, frankly, terrible art. And I usually enjoy old manga art, but this is terrible. The story is decent, I enjoyed it, but Crybaby did the story much better. Devilman can't be adapted because Devilman was already outdated just a few years after its release. A straight adaptation would feel anachronistic, played out and janky, the story moves in strange directions that don't work without some tailoring. Adapting Devilman accurately would be redundant, because shows that took cues from Devilman have already been made, and they were better. Devilman is worth a read for how important it was to manga history, it invented many tropes that we still see to this day, but the story is no longer anything special, and the art looks like a bad fan comic on DeviantArt.