Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

I know my comment won't answer your question regarding books, but you or anyone else reading this can message me any time to chat or ask questions about Japanese. I'm a professional translator in Okinawa.

Try Nyaa. Might have some material

wotaku.wiki

It can be considerably harder sourcing raw manga due to just your lack of familiarity with Japanese websites. Most of your searches will probably just end up being people looking up where to read Japanese manga translated into English. Wotaku might get you in the ballpark but you'll still probably need to source stuff yourself.

Honestly, what I've found easiest is to just set up a JP bookwalker account and browse that. If you're committed to piracy, just appending raw to your Google search for a Japanese title should do it but if the series you're after is niche it might be harder to find. Mangajikan is decent if you just want mainstream titles. Twitter is also great if you just want to find random stuff to read; authors frequently just post full chapters of their works. That's basically exclusively where we pull stuff to translate from, you get a really fun variety digging through random Japanese hashtags. Twicomi is a great frontend for that. Not sure on VNs, haven't read one in years.

When you do start reading, just stay committed. Not sure how long you've been learning Japanese but forming good habits from the beginning is essential. You don't want to take a day off, and then another, then a week... Good luck, I hope you get 日本語上手'd soon!

I use dlraw(dot)ac