The Ōsumi class (おおすみ型輸送艦), is a Japanese amphibious transport dock. The class is also known as the Oosumi class. While the Japan Maritime Self-Defense Force (JMSDF) describes the Ōsumi class as tank landing ships (LSTs), they lack the bow doors and beaching capability traditionally associated with LSTs. Functionally, their well deck makes the Ōsumi class more like a dock landing ship (LSD).

As of 2014 there are three Ōsumi vessels active with the Japanese Maritime Self-Defence Force.

JS Ōsumi (LST-4001) is the lead ship of the Ōsumi-class landing ship tank of the Japan Maritime Self-Defense Force (JMSDF).


At least two members of the class, Ōsumi and Kunisaki, participated in search and rescue and other disaster relief operations in the aftermath of the 2011 Tōhoku earthquake and tsunami.

In January 2014, The Japanese Ministry of Defence (MoD) confirmed reports that it will perform a major refit Ōsumi-class tank landing ships to embark MV-22 Ospreys, and Assault Amphibious Vehicles (AAV7s) to improve their amphibious capabilities. The MoD allocated JPY20 million (US$190,000) in its fiscal year 2014 budget to conduct research on the refit.

In 2014, Japanese Defense Minister Itsunori Onodera expressed the intention of buying one amphibious assault ship from the United States to provide more amphibious capabilities than the current Ōsumi class. A Wasp-class amphibious assault ship was most likely candidate for acquisition.

General characteristics
Type	Amphibious transport dock
Displacement	8,900 t (8,800 long tons) standard 13,000 t (13,000 long tons) full load
Length	178 m (584 ft 0 in)
Beam	25.8 m (84 ft 8 in)
Draught	17.0 m (55 ft 9 in)