For the longest time I thought Opera was a guy, not bc of the drawing design but bc when I started reading the manga in the version that I read (can't recall the website now) they referred to Opera as a "he" so I got stuck with it. It was only much later when I switched pages (in some sites the updates are faster) that I found out Opera is a non-binary character.
Translators can sometimes mix up some details along the way and it can really change a lot of the story, specially depending on which translated language you're reading it