I don't know about "seemingly boring", that's a pretty famous building in Shinjuku.
http://www.hiddenarchitecture.net/2015/05/new-sky-building-3...
It's in the post-war Metabolist style. If you want more of that stuff specifically, go where architecture students hang out. Ideally IRL...
There's also (again, specific to that style) a good recent book of interviews on Metabolism by Rem Koolhaas et al.
If you want brutalist architecture, @brutgroup on IG is pretty good: https://www.instagram.com/brutgroup/
Thank you for the link - exactly what I was searching !
I didn't know I want this site until now, I suppose this kind of stuff is on artsy Tumblr blogs but I don't know where to find those.