>>269860196Update from the future: not quite.
Japan is now required to pass domestic legislation that complies with the treaty.
When the treaty was drafted, Russia and China (among others) were pushing hard ban fictional minors; the proposed text explicitly included drawings, animation, even fictional audio and text that "exploits children". If that had passed, it would've already been Joever and loli (and any schoolgirl themes) would've be done for. But Japan (and in no small part due to Taro Yamada), the US, and a few other nations ironically managed to get that removed, and the resulting treaty ratified by the UN member nations didn't include it.
So right now the usual suspects (feminazis, extreme conservatives, etc.) are attempting to use this as an opportunity to ban fictional content that gets their panties in a twist. What happens next is anyone's guess. Whether or not that legistlation carves out an exception for fiction is up in the air.