It's no secret 46 year-old Gainax veteran and Trigger co-founder Hiroyuki Imaishi is a fan of American superhero comics. as along with other noted animators at those studios, he produced a pair of famous doujinshi on the subject. He also did a Hulk cover for Marvel's "Manga Month."
So, it shouldn't be surprising that he was enthusiastic about the debut of Justice League, and before that, Thor: Ragnarok, or as it's known locally, Battle Royale.
Check out his awesome fan art that he uploaded to twitter to celebrate the release of these films!
He also drew some art to go with the 10th anniversary rebroadcast of Gurren Lagann: