The Lambda 4S or L-4S was an experimental Japanese expendable carrier rocket. It was produced by Nissan and the Institute of Space and Astronautical Science and launched five times between 1966 and 1970 with Ohsumi technology demonstration satellites. The Lambda 4S consisted of four stages, with two booster rockets augmenting the first stage. SB-310 rockets were used as boosters, with an L735 first stage. The second stage was a reduced length derivative of the L735, whilst an L500 was used as the third stage. The fourth stage was an L480S. All of the stages burned solid fuel.