ばか！バカ！　馬鹿ー月！

Until now, I've never payed for ebooks. This is mostly because I was afraid of low quality and annoying DRM systems.
Recently I've stumbled across illustrations like these https://www.baka-tsuki.org/project/imag ... 2_0003.jpg which are really high quality. They don't look scanned at all so I'm guessing it's from an ebook.
So I was wondering if there good websites are to pay for accessing ebooks of LNs in Japanese to read on the PC. Is the quality the same everywhere? Where could that illustration I liked be from?

http://bookwalker.jp/st2/

All legal commercial ebooks have DRM though. But most rips that have been illegally uploaded are probably from bookwalker. It's owned by Kadokawa.
I buy all my LN ebooks from bookwalker and so far the experience is good. I even accumulated enough e-coins to get a few book for free throughout the last 3 years.