Its a bit of a shonen, but hitting shonen tropes isn't necessarily a bad thing. And Ranking of Kings does it in a relatively fresh way, and absolutely nails the "Brothers Grimm" style to fairy-tale magic and lore. (Yes, kid-friendly on the surface, but then deep blood-magic involving the grinding of bones and drinking of blood to infuse deep magicks into the story and lore). Bonus points that the battle scenes are done by the venerated Studio Wit.
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With regards to Gainax: their last big hit was Gurren Lagaan in 2007 IMO. But even Evangelion 3.0 + 1.0 was Studio Khara, not Gainax.
You're not wrong, but Gurren Lagaan is a great work, even if all those particular animators left Gainax shortly afterwards and started Studio Trigger. Most people consider Gurren Lagaan to be Studio Trigger for some reason but remember that group was still technically employed by Gainax when Gurren Lagaan came out.