In eastern Hokkaido, mainly around Nemuro, this has been fishermen's food for a very long time. The crab legs are scored with a knife so that the meat inside can be got at, simmered in kombu stock, and then seasoned with miso. That is the entire soup, and nothing further is added to it.

The name is the good part. Teppo means gun. Eating this involves poking away at the crab legs with your chopsticks to work the meat out of them, and somebody at some point decided that the motion resembles ramming a charge down the barrel of a musket. So the dish is named not after the crab, or the broth, or the place, but after what your hands do while you eat it.

Hanasaki crab has a fishing season of only three months, June through September, and nothing at all outside it. Eastern Hokkaido therefore ate this from summer into autumn and not otherwise.

Frozen crab changed that, and so did substitution: the soup is now made with kegani, with taraba, and with zuwai as well, and it is eaten right through the year. The gesture the name records is the one thing that has not changed. You still sit there with a wooden stick in your hand, loading and unloading a leg, exactly as somebody did on a boat a century ago.