As in most of the world's navies, Japan's earliest torpedo boats and destroyers had been small. It was only with the building of larger types, beginning with the Umikaze- class of 1911, that the Imperial Navy established the 1st Class (over 1,000 tons) and 2nd Class (under) designations to differentiate them. As Japan could not afford the large numbers of big ocean-going types that the navy would have preferred, the "medium" or 2nd Class Destroyer continued to be built. Only in July 1922 was it decided to abandon their construction. This decision was arrived at as a result of the unpopular Washington Naval Treaty, which led the IJN to adopt a policy of concentrating on fewer numbers of more capable ships rather than larger numbers of lesser ones.

Of the 112 destroyers with which the Imperial Japanese Navy began the Pacific War in December 1941, nine of the oldest and smallest were the last of Japan's "second-class" destroyers. These vessels of the Momi- and Wakatake-classes were fast but poor sea- boats, and carried only three 4.7" guns and four 21" torpedo tubes as main armament, though their depth charge stowage would rise from 18 to 60 as the war progressed. They were thus utilized primarily as local and coastal convoy escorts during the Pacific War.

(Many of their sister-ships had already been further downgraded in armament -- including removal of torpedo tubes -- and speed, and reclassified as patrol boats.)

HASU ("Lotus"), KURI ("Chestnut") and TSUGA ("Hemlock-Spruce") were the last units of the Momi-class, which had numbered 21 in the early 1920s, still soldiering on as destroyers in World War II. (Another nine of their sisters continued in service as re- rated Patrol Boats Nos. 31 - 39.) All three were administratively assigned to the Shanghai Area Base Force, China Area Fleet, where they were employed guarding maritime traffic and communications in coastal Chinese waters and on the Yangtse River, where their shallow draft benefitted them greatly.

But these little ships did take part in Japan's opening offensives. HASU teamed with gunboat TOBA (some sources also include armored cruiser IZUMO) to sink British gunboat HMS PETEREL at Shanghai on 8 December 1941. TSUGA supported the Japanese assault on Hong Kong that same month. And KURI assisted with the escort of shipping in Philippine waters and joined the blockade of Manila and Corregidor.

All three then reverted to patrolling out of Shanghai and escorting convoys between that port and Mako in the Pescadores through 1943. In 1944 their area of operations was extended to include Formosa and the Philippines, and the experiences of one of them in particular underscored the Empire's growing shortage of modern destroyers and desperate need for fleet-capable escorts.

TSUGA had just arrived in Manila with a convoy from Shanghai at the beginning of May 1944 when she was unexpectedly ordered to join destroyer HATSUSHIMO in escorting new fleet tanker HAYASUI to Davao. The three then remained together in Admiral Ozawa's 1st Supply Force, and with it took part in the Battle of the Philippine Sea in June. Doughty TSUGA came through the U.S. carrier air attacks on the supply forces of 20 June undamaged. (Though two of her charges, HAYASUI and SEIYO MARU, were hit and the latter scuttled.) She then remained with the tanker fleet to accompany it from Balikpapan via Manila and Takao back to Sasebo, where they finally arrived on 4 August. Only then was TSUGA released to return to her primary task of commerce protection in the China Sea. She would be caught at Mako and sunk there by U.S. carrier aircraft on 15 January 1945.

On 2 August 1944 HASU struck a mine in the Yangtse River and was left unmaneuverable. She was gotten to Shanghai for emergency repairs though the end of September, then was moved to Hong Kong. There she suffered further damage on 15 January 1945 -- the same day that TSUGA was sunk -- in another of that day's wide- ranging attacks by American aircraft of TF 38. More fortunate than her sister, HASU returned to Shanghai to finally complete repairs to her damage on 20 March 1945.

HASU then rejoined KURI in escort and transport work along the South China coast until advancing enemy airpower forced abandonment of those routes. On 25 June they retreated to Tsingtao to screen traffic along the North China coast, and survived the war undamaged in that port. KURI was mined and sunk postwar in October 1945 near Pusan, Korea, and HASU was eventually scrapped in 1946.

There were also six of eight Wakatake-class destroyers still operating as such on the eve of war (plus one re-rated as Patrol Boat No. 46), equally divided between the 13th and 32nd Destroyer Divisions. Desdiv 13 comprised WAKATAKE ("Young Bamboo"), KURETAKE ("Black/Dark Bamboo") and SANAE ("Rice Seedling"), and was assigned to the Kure Naval District. These ships were charged with antisubmarine patrolling in the waters of the Inland Sea, Bungo Strait, and western Kyushu. Desdiv 32 of ASAGAO ("Morning Glory"), FUYO ("Rose") and KARUKAYA ("Sage") came under the Chinkai (Korea) Guard District and spent the war's early months screening maritime traffic in the Tsushima Straits area.

The Imperial Navy made its first concession to the need for increased commerce protection on 10 April 1942 with the formation of the 1st Surface Escort Division, Southwest Area Fleet, and Desdivs 13 and 32 were assigned to it on that date. The convoy routes they worked were initially those between Japan (usually Moji), Formosa, and the Philippines, later extended to include Singapore, Indochina, the East Indies, and Palau. On 10 December 1942 Desdivs 13 and 32 were disbanded, leaving the six destroyers to operate directly under 1st Surface Escort Division command.

The Wakatakes thus went to work patrolling and guarding the Empire's vital shipping lanes to the "Southern Resources Area," duties which would generally consume the remainder of their wartime careers. In the course of this service KARUKAYA would set an IJN record by successfully completing 54 convoy escorts before her loss.

Not surprisingly, four of the five Wakatake-class war-losses were victims of American submarines. SANAE (sunk November 1943 by BLUEFISH), FUYO (December 1943 by PUFFER), KARUKAYA (May 1944 by COD) and KURETAKE (December 1944 by RAZORBACK) were all lost in torpedo attacks on their convoys, and all in the sub- infested waters around the Philippine Islands.

30 March 1944 found WAKATAKE herself at Palau -- and so did U.S. carrier planes of TF 38. WAKATAKE has long been recorded as having been blown up and sunk by aerial torpedoes well out to sea from the atoll while trying to escape, while her near-sister, Momi-class Patrol Boat No. 31, was sunk within. But now these identities appear to have been reversed. Recent research on the Palau shipwrecks by Dan E. Bailey has revealed that the wreck thought to have been that of Patrol Boat No. 31 in fact carried torpedo tubes -- all of which had been removed from the patrol boat conversions before the war. Furthermore, he uncovered a post-raid Japanese signal contemplating WAKATAKE's salvage -- clearly not an option with a deep-sea wreck. So it now appears that WAKATAKE never in fact made it out of the lagoon, but was sunk while attempting to shelter in a small inlet of Babelthaup Island. And the unfortunate escapee blown up at sea without trace or survivors was Patrol Boat No. 31.

ASAGAO kept just as busy as her sisters but was far more fortunate. 1943 saw her "touch port" with convoys at Moji, Mako and Takao a half-dozen times each, Manila four times, Palau twice, and Balikpapan once. She had just arrived in Camranh Bay with a convoy from Takao in January 1944 when fabled destroyer AMATSUKAZE was torpedoed and heavily damaged nearby in the South China Sea, so ASAGAO was called upon to tow the wreck back to Cape St. Jacques. She was back at Takao by late February to resume her convoy escort duties between that port, Manila, and Hainan.

On 9 July 1944 ASAGAO ran onto a reef near Hainan during a typhoon and remained stranded there for a full three months. On 29 July the immobilized but still-lucky destroyer even weathered attacks by an estimated 40 enemy aircraft without further significant damage. Only on 15 October 1944 was she finally refloated and returned to Japan for repairs near the end of the year.

By April 1945, after a brief final stint of patrol/escort duty out of Takao, ASAGAO was back in the Inland Sea, to serve out the remainder of the war as a "mother ship" to small patrol craft and minesweepers. Even there she was not safe, for on 22 August she suffered severe mine damage near Shimonoseki. At war's end the plucky little destroyer was surrendered there in a flooded and unnavigable condition.

ASAGAO was finally broken up at Yoshimi in 1948, bringing to a close a remarkable twenty-five year career, and ending the story of Japan's long-serving Second-Class Destroyers.