Nintendo DS Game Card eraser
From Starfy Wiki
Nintendo DS Game Card erasers (Japanese: ニンテンドーDS ゲームカード型 消しゴム) are miniature Nintendo DS game cases. Each one contains an eraser shaped like a Nintendo DS Game Card. Each eraser is a certain color depending on the game. They are available inside of capsule toys from vending machines throughout Japan.
One of the Nintendo DS Game Card erasers is based on Densetsu no Starfy 4. The eraser itself is pink.