If you're asking about the novel '18', the most secure route is through its official publisher's website or app. I checked, and it's available on Kobo and Amazon Kindle. Both platforms let you buy the full book or use a subscription service like Kindle Unlimited if it's included.
You can usually read a sample chapter for free before deciding. That's what I did. I liked the writing style in the preview, so I just purchased the whole thing. Reading it directly in the Kobo app felt smooth, with no formatting glitches. Plus, you know the translation is the official one, and your payment actually supports the author.
I steer clear of random sites that offer 'free' downloads. They're often riddled with pop-up ads and sometimes malware. It's not worth the risk for a book you can get legitimately for a few bucks.