Rurio was one of Momotaro's animal companions until his defeat by Hoozuki's hands. Now he works in Animal Hell together with his friends Shiro  and Kakisuke.

(Source: Hoozuki no Reitetsu Wikia)

Hoozuki is the aide to the great king of Hell, King Enma. Calm and super-sadistic, Hoozuki tries to resolve the various problems in Hell, including a rampaging Momotarou and his companions. However, he also likes spending his free time on his hobbies, such as fawning over cute animals and raising "Goldfish Flowers."
 
(Source: Crunchyroll)

The second season of Hoozuki no Reitetsu. 

As the right hand man of the Great King Enma, Hozuki’s job is literally a living hell. As the most competent demon in the underworld, it’s up to him to solve problems and invent new forms of hilarious and excruciating torture. 

(Source: HIDIVE)

The second cour of Hoozuki no Reitetsu 2.

In the afterlife, there exists Heaven and Hell. Hell consists of the Eight Greater Hells and the Eight Cold Hells, which are further divided into 272 subdivisions. Spearheading the seemingly endless, multifarious affairs in this gargantuan Hell is but one Fierce God, King Enma's first aide, Hozuki. Between this cool-headed sadist and his colorful band of peers, every day is a riot in Hell! And though this book might make Hell seem like a happening place, please try to behave during life!
 
(Source: Kodansha USA)

Bundled with the limited editions of volumes 29-31 of the Hoozuki no Reitetsu manga.