Oyster is eaten in Europe and loved by European too but probably European likes raw oyster. Although raw oyster is eaten in Japan, raw is unfortunately not the most common way to eat the oyster.
Major ways to eat oysters in Japan are; steamed, raw and fried. Then, fried is mostly the favorite way to eat the oyster. Fried in this case is not pan fried but deep fried in oil, oyster covered with breadcrumbs.
Japanese love deep fried dishes, and deep fried can be either with breadcrumbs or with batter as like tempura. Shrimp and cuttlefish can be in both styles but it is interesting that tempura style oyster does not exist. Therefore fried oyster should be eaten either with tartare sauce or brown sauce called CHUNOU sauce.
Due to oyster's season is from autumn to spring, fried oyster is mostly seasonal menu. Therefore if you are traveling in Japan during this period, you should definitely try the fried oyster.