Grisor was a mamodo trying to get the mamodo mirror. he was a small, blue, imp-like mamodo. He hired Cut n' Paste to help find the mirror pieces but he was defeated by Zatch and Kiyo. Grisor told Shion and Nya into helping him get the mirror pieces by telling them it would remove them from the contest for king, allowing them to stay together. When Zatch, Kiyo, Shion, and Nya brought their two mirror pieces to combine with his, he distracted them and ran away with the mirror. They caught up with him, but Dr. Hakase used a spell remotely by speaking it into a radio, with which Grisor targeted a radio-like invention of the doctor's to create a smokescreen.
Dr. Hakase revealed that the mirror was taken by Grisor to the human world, and that it true purpose here was to help Grisor become king. Hakase used it to reflect one of Grisor's spells, transforming Grisor into a large, purple, ogre-like monster (鬼 oni). His previously insignificant spells were now made 100 times stronger by the mirror. Nya attempted to fight him, but he burned her book with his new power. As Shion and Nya shared a tearful goodbye, Zatch and Kiyo promised to defeat him. Grisor showed off his immense strength, easily withstanding and overpowering his enemies' attacks. Shion attacked Hakase, knocking the mirror from his hand, which he quickly recovered. Grisor uses his most powerful spell, transforming into an enormous fiery demon, and fought against Zatch's Baou Zakeruga. Hakase discovers that Shion cracked the mirror, weakening Grisor. With its final bit of power, Zatch's spell defeats Grisor.
Dr. Hakase, whose real Japanese name is Fusaichi Ichirō (房市一郎), was Grisor's spellbook owner. Hakase was a famous scientist, having written many books, but was kicked out of some sort of organization by his colleagues, vowing revenge. Hakase met Grisor, and although their power was weak, he made machines to strengthen the spells to an extent. Hakase, sometime after meeting Grisor, implanted metal onto parts of his face, possibly because of injury from mamodo battles. Hakase set up a hidden lab within his new apartment, including a camera set up all over the city.
Description: After using the Magic Mirror, Grisor transforms into a fire oni, with much more strength than before. Grisor's strongest spell.
In the original Japanese series, Dr. Hakase's name was Ichirou Hakase, which means Dr. Ichirou in Japanese (Hakase meaning "Doctor"). Due to an error in translation, his name was translated as Dr. Hakase, basically, Dr. Doctor.