The strongest assassin against heroes! The weakest fluffy one of the Four Heavenly Kings (・ェ・`U)

In the otherworld of Yugna, where humans and demons wage fierce warfare, the Demon King's army—hoping for peace—is granted a fluffy creature by the goddess. The weakest of the Four Heavenly Kings, yet the strongest assassin against heroes, is born. "Kukuku, can you cut down Lord Wanko?" Can the hero Cain truly defeat this terrifying assassin? This is simply a story that the author Inu Mofu wanted to write.