He's always peeved at how Kiyo always gets 100%, so he plots new ways to try to make sure Kiyo gets a bad mark or look bad. For example, he put a nonsense question in the pop quiz that Kiyo was sure to get wrong, and made that question worth 30 marks out of the overall score. He also gave a test with unreasonable questions but with the help from Zatch, the principal caught him. He once wrote a book about Marie Antoinette and once gave Kiyo a test question asking what was the name of his cat Kiyo was able to figure out from that fact that he named it after her but shortend the name to Marie.