I have a friend who went to see this film 26 times—an absolute legend.
That friend is probably reading this article too, so I can't write anything careless.
Now, Shin Kamen Rider is the latest in the well-known series of Hideaki Anno's "Shin" films, the fourth entry following Shin Godzilla, Shin Evangelion, and Shin Ultraman.
Takeshi Hongo is abducted by a mysterious organization, but urged on by Ruriko Midorikawa, the two escape the research facility together by motorcycle.
Along the way, Ruriko is captured by the pursuing Spider Aug and its underling combatants.
Takeshi Hongo transforms into Grasshopper Aug, slaughters the combatants in the blink of an eye, rescues Ruriko, and hides out in a safe house.
There, Ruriko's father, Hiroshi Midorikawa, appears and reveals that he upgraded Hongo's body into one with immense lethal capability—the masterpiece of an insect-synthesis augmentation project that transforms its subjects using the power of the bio-energy Prana.
Hiroshi tells Hongo to use that power not for personal ego but for the sake of others, to stand against the organization they themselves had left—but then Spider Aug appears and kills him. Pursuing Spider Aug, who has once again carried Ruriko off, Hongo wraps around his neck the red scarf Ruriko gave him as a symbol of a hero, names himself "Kamen Rider," and defeats Spider Aug.
The film often gets panned, but the story faithfully follows the original manga and TV series, and is brilliantly rebuilt.
Here's a bit of trivia: in the TV version, Hiroshi Fujioka, who played Takeshi Hongo, injured his leg during filming, making shooting difficult, so Takeshi Sasaki, playing the second rider Hayato Ichimonji, was hastily brought in. The way the second rider appears this time around is crafted so that, if you know that bit of Rider 1 history, you'll find yourself smirking knowingly.
Now, on to the score.
Last time I covered the Shin Ultraman original soundtrack, and I described it as pretty edgy—it used the original series' source recordings as-is, among other things—but this one is comparatively conventional. ...That said, there's still plenty of music that pays homage to the original, with three versions of "Let's Go!! Rider Kick" included.
By the way, the composer this time is Taku Iwasaki. He's known for the score of the Rurouni Kenshin OVAs Trust & Betrayal and Reflection, as well as Gurren Lagann. I first came to know of him through Gurren Lagann and thought, what incredibly cool music this person makes—and seeing that he can also write music like this made me really appreciate just how amazing he is as a composer.
Now, let's listen to the music.
First is "metamorfose," the music that plays when Takeshi Hongo "transforms (metamorphoses)" into Kamen Rider.
Next is "Falling velocity," a piece built on the foundation of "Let's Go!! Rider Kick" but with no vocals—a song crafted from the BGM alone. This one's cool too.
Finally, let's part ways while watching the trailer for Shin Kamen Rider.

Image from the official site: https://www.shin-kamen-rider.jp/index.html