Cute, strong and tsundere is attacked by × Sister Yu's charming and powerful attack
""Rust"?"
"It will only turn red if you embroider it!!"
"Are you implying something else from me?"
"You are called rust because you are gold-plated in the draft..."
[There are no prototypes for each character in this article, so substitutions are declined]
Concept: Metal will oxidize and rust, so your heart is not metal.