Koumori 蝙蝠 is a lightweight yet powerful web browser which runs just as well on little embedded computers named for delicious pastries as it does on beefy machines with a core temperature exceeding that of planet earth. And it looks good doing that, too. Oh, and of course it’s free software. Koumori is a fork of Midori 9.0 with additional features, mainly because the original Midori is dead (website doesn’t exist, the name has been taken by the Astian Foundation and used for a DuckDuckGo web browser fork).
Koumori is not related in any way with Blink (Chromium, Chrome), Gecko (Firefox), DuckDuckGo or Astian Foundation. It uses WebKit, so its closest relative would be Apple’s Safari.