The Monster Kid

is a Japanese manga by Fujiko A. Fujio which adapted into 2 anime series.

The first anime series in monochrome was broadcasted on TBS from April 21, 1968 to March 23, 1969. The second series in color was broadcasted on TV Asahi from September 2, 1980 to September 28, 1982.

Plot
Taro Kaibutsu, otherwise known to others as Kaibutsu-kun and his companions, Dracula, Wolfman, and Franken, travel from Monster Land to the Human Realm, where they encounter and battle several monsters, mainly assassins from the demon group Demonish.