
For those interested in this story I highly recommend watching a documentary on the Kowloon walled city such as this one: https://www .youtube .com/watch?v=4YuNvIfM-YA
It really puts into perspective just how densely packed the city truly was, the living conditions, the city's history and eventually the end of it. Really feel for the characters' struggles, especially Weijing.

Does anyone know how to get the side story (in english or japanese is fine)

Yes, this one! https://www.cmoa.jp/title/252945/vol/2/
I was so looking forward to this but it just felt underwhelming, emotionless and cold. Where did all the build up and slow teasing go? The emotions, all the wait. This felt wrong.
Ikr. It's like a song where you expect a bad ass beat drop after the buildup but it just doesn't do anything. It was very lukewarm ngl. The foreplay went super fast, first round went super fast. It was like skimming through a badly written book
Also taehwan mentioned