"SSSS.GRIDMAN" is one of the new anime that my friend and I have been watching this season, and it's apparently so epic that it has to be expressed in full caps. From what my buddy explained and through Wikipedia, this Fall 2018 anime is a combination of the original tokusatsu series from the 1990s and the US adaptation of that series which came out soon after as "Superhuman Samurai Syber-Squad" which would explain the quadruple S at the front of the title.
Not being a fan of squabbling and taciturn student anime, I wasn't exactly all that impressed with the first episode, but once Gridman came into the scene and the kids started getting their act together for the sake of humanity, things started looking better.
Remembering the old tokusatsu shows from the 1970s when I was a kid, the opening theme songs were always arranged as a proud battle march with kids' choruses to amplify the fact that the hero was there for the children viewers. Nowadays, I think the only tokusatsu on regular TV has been the long-running "Kamen Rider"（仮面ライダー）franchise, and it seems like the opening themes have taken on more of an uptempo pop/rock kick.
That seems to be the case for the opener for "SSSS.GRIDMAN", "UNION" by the duo OxT. The pair consists of Japanese musician/composer Tom-H@ck and singer-songwriter Masayoshi Oishi（オーイシマサヨシ）. Oishi provided the super-cheerful opening theme for last season's wacky "Back Street Girls ~ Gokudols"（ゴクドルズ）, but this time, he and Tom-H@ck have come together to bring about this song of rock-driven optimism and hope in tribute to the title character and his support alliance of high school kids and unusual super-agents/mecha. This time, it is Oishi behind both words and music.
Now, OxT's 9th single under their current name (previously in 2013 and 2014, the collaboration was known as Tom-H@ck featuring Masayoshi Oishi) won't be released for another couple of days, so it's just the opening credits for now.