Born in New York, 1963, Leonard joined the Japanese Taiko drum group, Kodò in 1984, for which he served as the principal player, music director as well as composer. Leonard wrote several pieces of the Kodò's most celebrated songs including "Zoku" and "Irodori".

In 1992, Leonard left Kodò to pursue a solo career, and thereafter produced his own projects such as the Leo Project, which incorporates dance and live painting and his improvisational performances in Club"Leo". One of the unique qualities that defines Leonard’s artistic character is his exchanges with international artists which have taken him to over 35 countries. 1994 was a special year for Leonard for he won high acclaim for his performance with such greats as Bob Dylan, Michael Kamen (composer), Bon Jovi, The Chieftains, INXS, Ray Cooper, and Roger Taylor (Queen) at "The Great Music Experience" at Todaiji, the temple of the Great Budda, in Nara, Japan. Through his participation in the "MEGADRUMS" Europe tours (1990, 93, 99) as well as a variety of festivals and recording sessions, he performed with such world-renowned artists as Zakir Hussain (tabla), Andreas Vollenweider (harp), Milton Cardona (per.), Doudou Ndiaye Rose (per.), Max Roach (ds.), Michael Shrieve (SANTANA), Siouxsie Sioux, The Creatures and others. 2004 became yet another year of expedition for Leonard: he joined Siouxsie Sioux’s U.S. tour and London concerts as special guest and earned much recognition; furthermore, he toured South Africa, Madagascar, Bahrain, and Kuwait with his Taiko ensemble, Leopro.

Leonard’s musicality is articulated by H. Kawasaki of Mainichi News Paper as follows: “The luminous, festive essence and primal joy in Leonard’s music can easily transcend ethnic barriers. Just let yourself flow with the freedom manifested as the sounds he creates - that is all you need to do.” Together with his ample experience overseas, Leonard’s universal musicality has played the crucial role as the foundation of his activities.

Yet another feature to Leonard's unique make up is the originality of his musical creations. His original works have been featured in such Hollywood film productions as "JFK", "The Lion King" ,"The Hunted" and "The Thin Red Line", and they have also been used in ballet performances by Nina Ananiashvili, with whom he performed in 1998 and Patrick Dupond, as well as for the figure skating performances of Elvis Stojko.
"Tsu-Ku-Tsu", a work specially commissioned by Pilobolus, the renowned American modern dance company, has quickly become one of Leonard's representative works. "Tsu-Ku-Tsu" premiered in Boston in May 2000 and opened to critical acclaim and enthusiastic audiences in New York at the JoyceTheater in June 2000, where it enjoyed a three week run. A.J Hewat of the New York Times raves, "He's got rhythm, They've got moves: It's a fit".

The greatest influence on Leonard's music has been the environment in which he grew up. His father, Kimio Eto is the founder of the Ikuta Eto school of Koto playing, and he had performed with such big artists as Leopold Stokowski and Harry Belafonte.