Osaka Suzuki was founded in the late Edo period. They manufacture products applying the traditional techniques, where they cast into a mold and grind using potter's wheel. Tin came to Japan around 1300 years ago. It is known to have a great ion effect and it removes zatsumi (unfavorable tastes in sake) from sake, turning the taste milder. Thus, it is said that Osaka Suzuki's cups, which are made of tin, make alcohol's taste smoother.
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https://www.shokunin.com/en/osaka/guinomi.html