Scraping tuna with a clam shell is a traditional Japanese method called Nakaochi, where diners use the curved edge of a clam shell to scrape the soft, tender meat from the tuna's bones and ribs. This technique is used to prepare "nakaochi," a minced or finely chopped tuna product, and is also a popular way to serve a whole tuna rib in restaurants, often to be made into hand rolls, or temaki.

At one of my favourite Izakayas near Yoyogi station. They have some generous pours for high balls as well.