It's name is weird, but it's called Floorp.
It's very neat and interesting, made by just a couple highschool students over in Japan, and I have to say, I really love it. It takes a lot of cues from the likes of Vivaldi, which is a browser I once used before being forced back to Firefox because of nasty TDR issues I frequently experience on Windows when it comes to chrome based browsers. I also REALLY loved how much I could customize the UI. So, to have that, but in Firefox's engine? Yeah, I feel well fed.
Keep in mind though it's all in Japanese (Don't worry, the browser itself is localized to English fine!), so you're gonna have to go ahead and translate any of the official pages, that includes the blog. Since the browser was made in Japan, laws there dictate that they literally can't take any personal information, and it doesn't seem like the fellas making this browser intend to anyway. You may wanna tweak what's on the sidebar, as one of the things happens to be for a social media site oriented toward Japanese speakers, other than that, it's got some good addons built in, and I read that the next version will have native vertical tabs!
Again, I must say, I am well fed with this browser, I think. They're doing a good job.
