L. japonica produced on the coast of former Minamikayabe-cho Town (present Hakodate City) is recognized as the top quality products, called by the brand name 'Shirokuchihama.'
旧南茅部町周辺（現在は函館市）に産する真昆布が最高級品とされ、「白口浜」という銘柄で呼ばれる。