But this was a relatively short set at a festival. It wasn't a full concert like their previous shows at O2 Academy Brixton (2014) and Wembley Stadium (2016).
And they probably couldn't get the rights to release it themselves even if they wanted to — that's not how festivals work.
EDIT: Oh, they just did another show at O2 Academy Brixton on Tuesday. Yes, with Sayashi. But it was another relatively short set, because the show also featured two other bands. So… <shrug>
Oh, poop. That's disappointing. I didn't realize that they weren't full concerts.
At any rate, I can still hope that they'll have Riho on whatever concert DVDs and Blu-rays they do release from this year's Japanese and American tours (and next year's European tour).
"Think of how stupid the average person is, and realize half of them are stupider than that." — George Carlin