@glynmoody Typically, the argument brought up for Japan is that censorship violates Article 19 / 21 of the Constitution (it contains a right to free expression).

However, neither the law or this right is limitless. For instance, if someone deliberately makes non-consensual porn of someone (ahem, not an imaginary character), that would be prohibited conduct, from what I've seen. There's more I could say but I'll keep it short for conciseness.

If they're doing that, maybe it's a Western spammer, as someone from there who I know would put it. It's also a bit suspicious, the Brits are hard to trust, they have a bad track record. It is also quite a dubious intervention. Of course, it's not implausible the authorities there tipped the Brits off about it.