Yokais were characters featured in tokusatsu products in my childhood along with kaijus.
We had two tokusatsu drama series with yokai characters featured which were strikingly impressive: Akumakun (1966-1967: 26 episodes) and Kappa No Sanpei Great Operation Yokai (Yokai Daisakusen) (1968-1969: 26 episodes).
Both of them were based on the manga products created by Shigeru Mizuki and produced by Toei Company.
Akumakun is about a boy nicknamed Akumakun (akuma means devil/demon/satan; kun is a Japanese honorific title) who can summon a devil named Mefisto and fights against evil yokais and kaijus with his help.
Kappa No (no is the word showing possession) Sanpei is also about a boy named Sanpei gifted with supernatural ability from the kappas whose member Sanpei saved depicting his fights against evil yokais during his trip searching for his mother captured by those yokais.
The boys who starred Akumakun and Kappa No Sanpei were Mitsunobu Kaneko (1957-1997) and Yoshinobu Kaneko (1955-present) respectively. Although both of them are Kaneko and their first names also sound alike, they are no kin.
Mitsunobu is also well known for his starring role as Daisaku Kusama in Giant Robo and Yoshinobu also gained popularity for his leading role as Aokage (blue shadow) in Akakage.
Incidentally Sanpei’s fellow kappa Rokubei in Kappa No Sanpei was acted by Fuyuhiko Maki who also regularly played Shirokage (white shadow) in Akakage.