City Pop (シティーポップ) is an old genre of pop music in Japan. It was very popular in the 80s and 90s. It began in the late 70s and kicked off in the early 80s.
Its also considered a predecessor to modern J-Pop (though it certainly has more of a sophisticated vibe to it compared to modern J-Pop). Various City Pop songs are sampled in many Future Funk songs. Famous City Pop artists include, Mariya Takeuchi, Miki Matsubara, Anri, Naoko Gushima, Tatsuro Yamashita, etc.
There are many City Pop compilations on YouTube for people to listen to, with channels such as Ganymede Cafe making 40 minute long compilations of City Pop songs. Many of these songs are played in the background of an old anime gif in loop. City Pop is a very aesthetic genre of music due to its casual and upbeat nature.
Despite the best years of City Pop being behind the genre, the spirit of it lives on as sometimes it'll be interspersed with Vaporwave (and a lot of Vaporwave artists will sample City Pop in their songs to invoke the imagery of sophisticated Japan on the rise in the 80's and 90's) and a lot of City Pop aesthetics will find themselves tied to the Lo-Fi aesthetic, thus ensuring City Pop's legacy in internet aesthetic history.
A lot of City Pop images depict shots of Japanese city life and nightlife during their opulent high life; sometimes the streets will be full of people without a care in the world and sometimes just empty, peaceful 1970's/1980's Japanese streets (giving a similar vibe to the After Hours aesthetic). Sometimes these photos can be stylistically edited to show more pops of Magenta, Cyan, Red, Yellow, Blue, and Purple.
City Pop fashion tends to be very opulent, high end, and draws a lot on the Yuppie fashion of the time (so a lot of J-Preppy and Resort style turns up in City Pop fashion). Indeed, a lot of City Pop fashion has served as inspiration for a lot of modern Japan-inspired aesthetics such as Vaporwave and Lo-Fi.
City Pop's musical style is heavily influenced by American soft rock (namely acts such as Steely Dan and The Doobie Brothers) by taking the song structures of the genre and mixing it with Southern R&B from the US, Northern Soul from the UK, and jazz fusion music to try and achieve an almost tropical and sophisticated sound (drawn heavily from the Hawaiian and Okinawan vibes in particular) born from the belief that the Japanese economy was only going to continue to thrive and grow and that the good times would never end (much like America's Roaring Twenties). The music in particular was also designed specifically to play in car stereos of the time (which were just starting to gain in popularity), which was a very unique idea at the time. While the genre faded out of style by the 1990's (largely due to the tanking of the Japanese economy in what came to be known as "The Lost Decade" and, arguably, Japan hasn't completely recovered from to this day), classic City Pop has seemingly found new life thanks to Vaporwave music (Future Funk in particular tends to love to sample old City Pop songs and transforming them into funky new tracks) and the fact the YouTube algorithm a while back decided to pick Mariya Takeuchi's "Plastic Love" to be the random video that turns up in everybody's feed to watch, which led to the song getting so popular that they decided to film a music video for the song 35 years after its initial release! Many anime fans from the 90's (when anime was just starting to take off in the West) might actually recognize a lot of popular City Pop artists due to a lot of the artists doing the themes for various anime that came out in the 80's and early 90's and the themes themselves generally carry a slight City Pop sound.
The spiritual successor of City Pop, Shibuya-kei, is a microgenre of pop music or a general aesthetic that flourished in the mid to late 1990s. Shibuya-kei initially fused French ye-ye, jazz, bossa nova, lounge music, funk, and 60's psychedelic pop into a futuristic retro-pastiche.