It is said that the family was established in the Edo period by Michiyasu KOGA, the Sangi (Director of palace affaires) and the third son of Michikata KOGA who was Dainagon (chief councilor of state), but there are several views on the origin of the Higashikuze family: some say that Michiyasu was the child of Boan SHIMOZU who was the child of Michikata and others say that Motohide was the grandchild of Harumichi KOGA and that the grandchild of Motohide was Michiyasu.
大納言久我通堅の三男・参議久我通廉によって江戸時代当初に創設されたとされるが、その他、東久世家の起源には諸説あり、通廉を通堅の子下津俸庵（下津俸庵）の子とする説や、または、祖秀は久我晴通の孫で、祖秀の孫が通廉とする説などがある。