The author is mistaken about the Emperor of Japan having no political power. His political power is so immense that he can wield it without having a law to back it up and he takes enormous amount of care to not use it accidentally.
As an example, about 10 years ago, he invited Japanese who had been kidnapped by North Korea to his Enyukai (something like a informal tea party) and offered his condolence. He did not say anything about North Korea in his condolence. Just that they had faced a hardship and survived. Since then, not a single Japanese politician had dared to suggest that Japan should lift any sanction against North Korea without the complete account and return of all Japanese who had been kidnapped by North Korea. This is what he can do by just saying “I feel sorry for you” without a trace of anger.
So, the Emperor of Japan is still the de facto absolute monarch whether he likes it or not. Just today, Communist Party of Japan affirmed this indirectly, by arguing that Japan should not have a casino because Empress Jito in 7th century warned against the danger of gambling and banned it. When even communists are praising the monarchy, you can see how much political power he can wield.