While Fire Emblem Echoes: Shadows of Valentia releases on May 19 in Europe, it comes out in Japan in two weeks' time, and some people have already managed to get their hands on a final cartridge and its inner game code. As usual, people then data-mined that code and found a good bunch of secrets reserved for the players, so from now on we could say the spoiler season is now open.
One of the first things to note is that, as previously rumoured, this release will also lead to the launch of new Smash Bros. amiibo figurines for both the female and male Corrin character. Apparently an additional chapter will also include character descriptions, a soundtrack, and more too.
That said, we'd recommend you to just avoid all this, play some more Fates or Heroes, and wait a bit longer until you can properly experience the real deal on your Nintendo 3DS in May. That way, you'll avoid spoilers and be sure you're safe. Do you wait to keep games fresh upon release, or do lots of research beforehand?