"So what is a shirasagi, anyway?" I asked the JR clerk in Nagoya Station who had initiated our rail passes and booked reservations on the Shirasagi Limited Express to Hida Takayama. "Could it be a white rabbit (shira- 'white' + usagi 'rabbit')?" She had no idea. But I should have known it would be a bird.
Before the advent of the Shinkansen bullet trains in 1964, the most famous limited express train along the Tokaido Main Line was the Tsubame 'swallow'. In fact, the Japan National Railways (JNR, 国鉄) used a swallow logo on its bus system and called its professional baseball team the (Kokutetsu) Swallows. Two other notable limited express trains we rode in those days were the Hato 'dove' and the Kamome 'seagull'.
Most express trains were named for destinations, like the Miyajima Express that I used to ride home to Hiroshima from boarding school in Kobe, but the fastest limited express trains tended to be named for birds. The first bullet trains went for even speedier names: Kodama 'echo' (speed of sound), Hikari 'flash' (speed of light), and the latest, postmodern-sounding Nozomi 'desire'. But regional bullet trains have revived a lot of the old limited-express bird names: Hayabusa 'peregrine falcon', Kamome 'seagull', Toki 'crested ibis', Tsubame 'swallow'.
On our latest trip, we were in the Hokuriku region, off the Shinkansen grid, where the fastest trains are traditional limited expresses, so we encountered several bird-named trains that were new to me. Shirasagi can be translated 'snowy egret' (Egretta thula), although sagi labels the whole family of herons (Ardeidae), as in aosagi (lit. 'blue heron') 'gray heron' (Ardeia cinerea).
Coming back to Kanazawa from Nanao on the Noto Peninsula, we rode the Sandābādo/Thunderbird, whose name left me a bit nonplussed until we paired it with Raichō 'rock ptarmigan' (Lagopus muta), a limited express that runs from Osaka through Kanazawa to Toyama. Thunderbird began operations as Super Raichō (Thunderbird), and Raichō (雷鳥) literally translates as 'thunder bird'. The rock ptarmigan is a symbol of Toyama Prefecture's Tateyama, one of Japan's 三霊山 Sanreizan 'Three Holy Mountains', along with Fujisan and Hakusan. (Doesn't the Rock Ptarmigan sound like a good name for a smaller version of Ford's SVT Raptor?)
Another limited express we rode between Kanazawa and Toyama was the Hakutaka, whose name is always written in kana, not kanji, and whose train cars carry an emblem with the English words "White Wing." The name evokes an old Tateyama legend about a white hawk (白鷹, which would normally be pronounced shirataka), but also evokes the name of a long-distance train, Hakuchō ('white bird' =) 'swan' that used to run all the way from Aomori (where the swan is the prefectural bird) via Ueno and Kanazawa to Osaka. The name Hakutaka was independently used for trains running on the leg between Ueno and Kanazawa until that leg was disrupted by the extension of the Shinkansen toward Nagano and Niigata in 1982. In 1997 it was revived for limited express trains running along the Japan Sea coast between Fukui and Niigata prefectures.
The first Japanese long-distance trains to receive names seem to have been the Fuji and Sakura, which began running between Tokyo and Shimonoseki in 1912, but were not named until 1929.
The first train named Hato 'dove' was an express on the South Manchuria Railway (満鉄 Mantetsu) running between Dalian and the new (in 1932) Manchukuo capital, 新京 Shinkyō (now Changchun). The limited express on that route was named あじあ Ajia 'Asia'.
POSTSCRIPT: The first trains named Hikari and Nozomi were Mantetsu expresses running between Busan (釜山) and Shinkyō (新京). (Japanese Wikipedia offers very detailed coverage of Japanese train systems, past and present.)
And, speaking of Imperial Japan, many of the same bird names were used for Hayabusa-class torpedo boats built between 1900 and 1904 that served so well in the Battle of Tsushima in the Russo-Japanese War.