The H-I, which drew on the results from the development of the N-I and N-II launch vehicles, is a three-stage rocket created for responding to Japan's satellite launching needs of the late 1980's.
The H-I's first-stage and strap-on boosters are identical to those of the N-II. The second-stage engine (LE-5) and propellant, third stage solid propellant rocket motor and inertial guidance system are all products of Japan's technology.
The H-I which was utilized in a total of 9 launches from 1986 to 1991 are no longer in use but the technology used in developing the H-I was exploited for developing the H-II.