Is Rin the worst-treated character in all of yugioh?
She is a key plot point, a key element of the lore of the show. But. She has 1 duel, in which she has no agency, she has 1 relationship, with a boy who loves her but we never see them interact in the show proper, she has… nothing.
She is gone. Dead. Forever vanished. Nobody will mourn her. Yugo was the only person that knew her, and they’re together inside Yuya and Yuzu maybe. Allan, Sayaka, Shun and Kite will deeply miss Ruri. Barret and the Lancers will mourn Serena. Rin.
Nobody knew Rin.
Did Yugo know Rin? He saw her as a love interest, he was infatuated with a childhood crush. And he lost the duel against the parasite because of that.
Her only legacy was building Yugo’s bike with him, which is destroyed and gone forever. Clothes that were clearly designed with Yuzu in mind due to the color palette. Those are gone, too.
She never got to see her city improve.
We never got to see what were her goals.
We never got to see her outside of being along the other yugirls rooting for Yuya.
And no character in universe will notice that she is gone.