Apparently it's quite rare for a country to have never been colonized.
The countries that have never been colonized include,
in Europe: the British Empire, Germany, Spain, Portugal, Italy, the Russian Empire (Soviet Union), and other Nordic nations.
In Asia, it seems to be just Japan and Thailand or thereabouts.

Japan is actually a pretty rare country.

Why am I bringing this up? Because this story is set in a near-future Japan that has been colonized by the Holy Britannian Empire, with the name 'Japan' changed to 'Area 11,'
and the people of Japan renamed 'Elevens.'

A brief synopsis goes as follows.
Seven years after the invasion of Japan, Lelouch Lamperouge, a Britannian boy living in Japan, is granted by a mysterious girl, C.C. (C2), the power of absolute obedience called 'Geass,' which lets him force anyone to obey his commands. To avenge his assassinated mother and create a place where his sister Nunnally can live in peace, Lelouch hides his face behind a mask, takes the name 'Zero,' forms the resistance group 'The Black Knights,' and wages war against the Britannian Empire. (Partially excerpted from Wikipedia.)

It's a thrilling, edge-of-your-seat mecha series where you can never see what's coming, and it always ends right at the good part.
The first season's finale in particular makes you gasp—'It ends THERE?!'

This work was later combined with the second season, R2, and released as a trilogy of compilation films, after which a 10th-anniversary work, 'Code Geass: Lelouch of the Re;surrection,' was screened.

Let me introduce the composers. There are two this time: Kotaro Nakagawa and Hitomi Kuroishi.
Kotaro Nakagawa has worked on anime, tokusatsu, dramas, commercials, and more. Among the Kamen Rider series he handled 'Kamen Rider 555,' 'Kamen Rider W,' 'Kamen Rider OOO,' 'Kamen Rider Wizard,' and 'Kamen Rider Drive,' and later, in the Reiwa-era Riders, 'Kamen Rider Revice' as well.
For dramas, he's scored numerous works, including 'Botan to Bara,' famous for its wallet-steak scene.

Hitomi Kuroishi, on the other hand, mainly composes her own music and sings it herself under the name Hitomi—a style seen throughout this very work, Code Geass: Lelouch of the Rebellion.
She also provided songs for works like 'LAST EXILE,' again composing and singing them herself.
Her voice is beautiful and crystal-clear, with melodies that are deeply soothing to listen to and at times tinged with sorrow, so they're often used in beautiful, emotional scenes.

Now let's give them a listen. First up is what could fairly be called the main theme, '0' (Zero), handled by Kotaro Nakagawa.

https://www.youtube.com/watch?v=1s14_TekLv0



Next is 'Stories,' composed by Hitomi Kuroishi and sung by her as Hitomi. Used as BGM in scenes that heighten the sorrow, it left all sorts of impressions on me.


https://www.youtube.com/watch?v=29uVEXQm41c



To close, let's part ways while watching the PV for 'Code Geass: Lelouch of the Rebellion I: Initiation,' which could be called the first part of the film trilogy.

https://www.youtube.com/watch?v=yLvlQPLAors
Code Geass: Lelouch of the Rebellion

Quoted from the official site https://www.sunrise-inc.co.jp/geas/