Alright, this test was made by me and can still be improved. Feel free to add more. But here we go. Count the number of yes for each category, so that you know how Japanese you are from 0 to 10 for each, then in total (Japanese are welcome to take the test too ) :

Food

Can you eat/Do you like (if you don't know what it is, then "no") :

1) Sushi
2) Natto
3) Hijiki
4) Oden
5) Tofu
6) Umeboshi
7) Takuan
8) Fried fish
9) Whale
10) Miso soup

Etiquette

Do you :

1) remove your shoes before entering your own house
2) slurp your ramen
3) excuse yourself all the time even when you are not wrong
4) bow (even slightly) when greeting or seeing someone off (in formal situations)
5) bow when you talk on the phone
6) buy omiyage for your colleagues, friends or family when you go somewhere (even for a few days)
7) nod or make little sounds agreement showing that you are listenning to someone
8) avoid teling people directly what you think
9) avoid putting soap or foam in your bath
10) refrain from eating in the street or while standing/walking.

Cultural adaptation

Can you :

1) Sleep on a futon
2) bear Japanese TV programmes
3) ride a bicycle with an umbrella in one hand
4) sit in "seiza"

Do you :

5) like J-pop
6) like kabuki
7) read manga
8) like sumo
9) like everything that is cute
10) like "onsen" (hot spring)

I am a little bit ashamed that I scored only 9-6-5 - but I was severe enough to exclude things I can't really do or don't really like. Actually, nothing bothers me very much, except the smell of natto. I can't slurp my ramen eventhough I try, can't refrain from eating outside or standing (and can't understand why Japanese have invented such stupid rules), then of course, I am too frank to have a tatemae side.