It's like Dororo's atmosphere and world-feel in Jamurai Jack's robot setting and episodic-ness with a sprinkle of [Mushishi] introspection in places. And fuck tonnes of post-apocalypse [Angel's Egg] darkness.
Stories of struggling swordsman in a country where people have been affected by war and demons. Guts & Hyakkimaru are very tragic characters who are destined to battle the evils of men and demon alike.
both of these series were made at the very end of the classic black and white era of anime (dororo to hyakkimaru was actually the last one made in black and white) - both are atmospheric, ahead of their time, and have dark themes including demons and yokai - both were originally from grandmasters of manga (dororo by osamu tezuka and gegege no kitaro by shigeru mizuki) - and both are great!