This piece of music (by series composer Kevin Penkin) is played at the start of the first episode of Made in Abyss in lieu of the standard OP, during an otherwise soundless montage of Riko and Nat heading home to Orth with Reg on Nat’s back.
“Underground River” and the montage that accompanies it, were all I needed to see and hear become absolutely hooked on Made in Abyss, albeit five weeks later than most others.
It perfectly encapsulates the show’s spirit of youthful adventure, as well as the excitement and bittersweet yearning that go hand in hand upon striking out into the big world, from the home you’ve always known.
(The vocals also remind me of Sohn.)
So far I think MIA is hands-down the best series of the Summer, excelling equally in story, characters, animation, and yes, music. I only wish this piece was the weekly OP (though the actual one isn’t bad either).