If you're looking for manga similar to Assobot Goku, you might like these titles.
In the mystical world of Shangri-la, demons and humans live side by side, watched over by a parthenon of ancient Chinese gods. But when normally-civilized demons start to go berserk, the gods require the services of Genjou Sanzo - a Buddhist priest with a magical gun, an evil-banishing scripture and a take-no-prisoners attitude. Aided by the ancient monkey god Son Goku, the half-demon Sha Gojyo and the demon exterminator Cho Hakkai, he sets off on a treacherous journey westward, with armies of demons, dark mages and angry gods all standing in his way...
Prime Rose is the story of a young princess/gladiator named Emiya who spurns the advances of the young emperor (much to the fury of her father) and through a series of adventures discovers that the Emperor is corrupt and vows his overthrow using the unusual ability that she discovers after an encounter with a seemingly homeless old man…
In the beginning, great gods reigned over the heavens and earth, and humans were enjoying peace -- until the warlord Taishakuten instigated a rebellion and slain the emperor, ushering in an era of darkness. Now, young Ashura, her protector Yasha, and friends Ryu, Sohma, and Karura make up five of the six stars of legend who are fated to bring down Taishakuten and restore peace to the world. On a quest to find the sixth star, they will encounter many dangers including an ice demon and even monstrous snakes, but can they stay alive long enough to save the world?
When the dark god of evil, Exodus, arises once more in the realm of Sosaria, it resurrects the evil magicians Mondain and Minax and with their aide threatens to plunge the land into eternal darkness. Its up to the four chosen "Dragon Warriors" of prophecy to defeat it: Genji, a futuristic space explorer; Aida, a peaceful, animal-loving cleric; Lennon, a paranoid and often disgruntled bard; and Bigelow, a mechanized robot with a capacity for human emotion.
Imagine a world where the insects of the Earth have decided to revolt and enslave humanity, and shrink them down to a size that would make them seem to be insects to the new Insect overlords. This new race of humanity is called Michroids, and they are trying to find their new role in the world…