The Leichte Schnellboote 4 (lit. "Light Fast Boat 4"), nicknamed Esau, was one of the 12 LS-class fast torpedo boats originally ordered by the Kriegsmarine as an ultra-light version of the larger S-class fast torpedo boat. The LS 4 was the first boat of the class to receive the up-calibred 20 mm MG151 autocannon as its main armament. After LS 4 was built at the Dornier Werft shipyard on 5 July 1941, it was assigned to be deployed from the auxiliary cruiser Michel, which went on to sink 18 ships, of which the Esau is credited for sinking the tanker ship Connecticut and crippling two others. After two years of commerce raiding across the Pacific, LS 4 was destroyed in the sinking of its mothership Michel on 17 October 1943 after an attack from the American submarine USS Tarpon (SS-175), marking the end of the last German raiders of World War II.

Introduced in Update 1.79 "Project X" as part of the fleet closed beta test, the LS 4 Esau is an upgunned variant of the LS 3. Although the up-calibred version of the MG151 autocannon provides worse armour-piercing qualities, it makes up for it with a significantly more powerful HE belt that, while not the infamous minengeschoß shell found on the aircraft version, is still powerful enough to shred any simple model boats into pieces. However, the Esau retains the key weakness of the tech tree version in the form of an easily overheated gun and overall poor survivability. This means trigger discipline and the use of the boat's agility are vital to its success.