Itching and redness when metal touches the skin is caused by sweat melting the metal.
Does sweat melt metal? It's a little surprising, isn't it? It doesn't melt into mush, but it melts just a little bit and just a little bit of metal comes out. (To be precise, metal ions come out.) Sweat, technically speaking, is called an "electrolyte", and it is a rather troublesome liquid that has the power to dissolve and corrode.
Metal leached from sweat causes itchiness and redness. Therefore, the role of the sweat barrier is to prevent metal from melting by preventing contact between sweat and metal.
By the way, the phenomenon that metal melts with sweat happens to everyone. Then why are some people itchy and others not? I will talk about it after the third time.
It's sunny in Nagano City today! Nagano in this season is refreshing and very pleasant.