If you're hunting for a legitimate place to read 'Under the Oak Tree, Vol. 1' online, I usually start with the big ebook stores: Amazon Kindle, Google Play Books, Apple Books, Kobo, and Barnes & Noble's Nook. Those marketplaces often carry licensed translations or official e-editions, and a quick search there will show if an English volume exists for purchase. I prefer buying the ebook so the original author and publisher get paid, and it’s painless to carry on my phone.
Beyond those, check your local library’s digital services—Libby/OverDrive or Hoopla can have licensed ebooks and sometimes even comics. For the manhwa adaptation, I read on platforms like Tappytoon or Tapas where licensed webcomics are hosted; they often list the source novel and link to official releases. Avoid random scanlation sites: they might be tempting, but supporting official releases keeps more creators working on things we love. I personally snagged my copy on Kindle and kept the manhwa on Tappytoon for visuals — it's one of those series I like revisiting for the character moments.