[RealJames]

foreigners can get away with much much more than Japanese people here...

Also, depending on where you're teaching, the employer may understand that the students generally want the authenticity over the Japan-afflicted version of a westerner to speak with.

As a teacher, I've had my hair died a few different colors, all natural though, and frequently had stubble for a few days while changing beard styles. None of it was even remotely negatively received. In fact it sparked good conversations about cultural differences in employment.

Tattoos are generally fine on foreigners, most people understand that from wherever they're from it doesn't mean the same as it does in Japan.

Consider also that many of those people learning English have either been abroad, are interested in going abroad, or require frequent contact with foreigners due to work etc. In other words, they know how it is elsewhere.

As a teacher, there's no prerequisite to wear a skirt lol. That's absurd.
Although I'd love to be the dirtbag boss that insisted upon it from his Japanese staff and female teachers... maybe it's time to revise that dress code! ;D