Dororon Enma-kun

Dororon Enma-kun is a manga and anime franchise by Dynamic Productions featuring the misadventures of Enma, the nephew of Enma Daio and his Yokai Patrol. Several anime adaptations and manga spin-offs were produced including Dororon Enpi-chan which features a teenaged female version of Enma as well as several crossovers including with Osamu Tezuka's Dororo.

Summary
Enma (nicknamed Enma-kun), nephew of Enma Daio leads a Yokai Patrol with his childhood friend Yukikohime, Kappaeru, and the talking hat Chapeauji to hunt down villainous yokai that escaped from Hell and are tormenting humans on Earth. At times he works together with humans including Tsutomu-kun and/or Harumi. While the original format and similar series were more like gag manga, more mature releases such as Kikoshi Enma are more series and dark.

Dororon Enma-kun in Mazinger

 * Enma-kun and the Yokai Patrol appeared in the crossover manga Dynamic Heroes.
 * Enma-kun and the Yokai Patrol appeared in the summer festival chapter of Mazinger Angels after hunting down Yokai that snuck in. Yukikohime is noticeably much older than her original counterpart and Kappaeru bears a more kappa-like appearance.
 * Enpi-chan appears as a fortune teller in a chapter of Shin Mazinger ZERO vs. Ankoku Daishogun, foretelling a great disaster.
 * Robot Girls Z ONLINE featured a special campaign where an inverted version of Enma-kun called Enmako-chan appeared in-game.