Observation from the Duolingo Japanese course:
If a sentence translates as “My girlfriend’s older brother is a an elementary school student”, you should probably go back to the drawing board.
In this case, a fellow student made this translation with “彼女 の お兄さん は しょうがくせい” (Kanojo no oniisan wa shougakusei) and commented, rightly so, that “This ain’t right.”
Grammatically it is possible, I suppose, since “kanojo” can mean both “she” and “girlfriend”, but it sure ain’t *right.* Also we haven’t learned the “girlfriend” translation yet. So he probably picked up that from anime or manga.
As an anime character so aptly put it: “A little shoujo manga is a dangerous thing.” I hear several people tell that the Japanese you learn from manga and anime is not entirely safe to use around actual Japanese people. Perhaps it is better to think of it as a special dialect that you only use among your own kind.
(Yes, I am aware that manganese is a chemical element found in the periodic table. I just used the word as a pun on “manga” – comics – and Japanese.)