I'm surprised that so little people watched this film and again surprised that most people probably watched it not having a proper understanding about Korean Japanese and their culture in Japan.
Long story short, after Japanese colonization period in early 1900s, quite a bit of Koreans remained in Japan, most of them unwillingly because they either lost their families in Korean War that soon followed after the Liberation of Korea from Japanese rule and had no families to go back to, or because they've already made families and started a living in Japan so it was too late for them to return to their homeland Korea since they had nothing there. Plus, Korea was also devastated terribly from the effects of Korean War, so Koreans living in Japan thought they should just stay in Japan, hoping that one day they could visit Korea when things calm down and they make enough money to return to home country.
This movie is deeply rooted in those sad, terrible, and complicated backgrounds of Korean Japanese history, so watching this movie without that knowledge would make this movie seem weird, or hard to follow on surface level.
The "Dragon" family depicted in the movie has most of those various backgrounds, and the story unfolds as each member tries their best to make a living and to survive/prosper in Japan as a Korean Japanese.
Korean Japanese to this day are still discriminated by some Japanese to certain extent because they used to be treated unjustly during the colonization as a lesser being than a Japanese, making it difficult even today for Korean Japanese to advance into higher places in the Japanese society.
Imagine then, how worse the racial discrimination and prejudice against Koreans would've been for the family depicted in this movie that is set 50 years ago (just like how it was like in the U.S. during 1970s with all the hate crimes and Civil Rights movement).
My advice for those watching this film is, please watch this movie, more as a historical documentary film with fictional characters, than just for a pure entertainment value.
You might just find a gem in this masterpiece then.