You've probably also seen it in the film Grave of the fireflies of Isao Takahata (studio Ghibli) or so in Dagashi Kashi, Sakuma Drops. These are fruit candies that have the peculiarity of being contained in a metal box or sort of can. The cap of this is very hard to open, you must use a lever ( a coin or a metal spoon ). And yes, as they are good, you have to deserve it LOL.

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