You can buy the official manga on sublime.com! All the previous volumes are there too ;) I always buy their works there!
In my country they're also available on Amazon which might be a better option depending on where you live.
I’m a minor and my parents are Christian and we share an Amazon account… they also check all my packages due to an incident of long story short me buying something I shouldn’t have. So that’s not an option :(
I do have a job though which is how I’m gonna pay for it
This is so my good I love it legit my reason for living. How can I support the author financially?