Mai and Anko.
Shouldn't the mesh fabric be completely see-through? Why wear a shirt at all at that point?
Did a little research:
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First, let's take a look at Anko:
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Then let's take a look at a relatively short list of characters who wear the same material:
Akatsuchi, Kurotsuchi, Onoki:
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Deidara:
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Fourth Kazekage:
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Gaara:
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Hinata:
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Ino:
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Jiraiya, Oro, Saru, Tsunade:
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Jiraiya (Older):
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Kiba:
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Konan, Yahiko, Nagato:
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Kurenai:
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Mei:
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Minato (And possibly Kushina):
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Onoki:
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Shikamaru:
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All shown wearing the same "fishnet" material. Many of them in several different shades, but all dark, and all remarkably similar to other metal materials such as their forehead protectors, zippers, kunai, shuriken, etc. It's also curious that in those where several characters are standing next to each other, the "fishnet" is typically the exact same color and shade, even when the characters in question have drastically different skin tones.
Now let's take a gander at Temari.
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Note the distinctly different appearance between Temari's clearer fishnet, and the dark grey, silver, and black garments worn by so many others, most of which are completely filled in with that single color.
Another thing to note is the locations where most of these are worn, often in separate pieces rather than in one large piece: Chest, knees, shins, forearms, elbows...the kind of places used to strike and block. The same kinds of areas where multiple ninja are seen placing wrappings (Ex: Lee) or heavier pieces of armor (the flak jackets). I mean heck, even their summons have been seen donning the stuff:
Enma:
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Gamaken:
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So either they are a metal mesh serving a practical defensive purpose of some kind, or there is a fishnet obsession in this world seen only among ninja that transcends generational gaps, national boundaries, and even entire species.