Tomiki Sensei, in 1949 was a professor at the prestigious Waseda University and also headed up the Judo school there.
He also taught Aikido or "Judo-Taiso" to some judo students after normal Judo training ended, as an unsanctioned "Doka-Kai". (Doko-Kai”, meaning a loosely organized club made up with people of the same interest.)
Unsanctioned sport clubs (Doko-Kai) had neither the prestige nor the status of sanctioned clubs such as Judo, Kendo, Karate, baseball, soccer and other major sport clubs.
All Students at Waseda were at that time required to join a sports club as part of their syllabus, so it was an ambition of Tomiki Sensei to promote and establish Aikido as a legitimate option of study for students at the university, which could only happen if he could establish a "recognised" Aikido club.
To become a recognised or sanctioned sports club at Waseda there was a stipulation that a method should exist to measure and/or judge the progress and ability of students, and that any clubs belonging to the official Athletic Association must have a formal syllabus and form of competition of some fashion.
This stipulation led to Tomiki sensei, adopting the methods of Kano Sensei (by which he formed sports safe techniques for Judo from the martial art of Jiujutsu) to arrive at a "sanitized" set of Aikido techniques suitable for Randori-ho.
By 1952 he had between 12 and 15 techniques developed and a workable competition format, such that in April, 1958 Waseda University approved his Aikido Club as an officially sanctioned sport club (called “Undo Bu” in Japanese), while no other universities recognized any Aikido clubs as such.
In May 1956 Tomiki Sensei published a book on Judo that has an appendix on Aikido where he writes about this work and details 15 techniques or principles for randori use in Aikido.
From this starting point the Randori-no-Kata (ju-nana hon) we are familiar with was developed.
in Tomiki sensei's own words:-
It is important to recognise that the "Randori-no-Kata", is as the name suggests, primarily a kata for randori practice, and should be viewed in that light. The techniques themselves are not meant to represent a complete style or Ryu-ha of aikido, they are actually a small subset of techniques that have been approved for Randori practice and competition.
However, by breaking aikido down in this manner, Tomiki Sensei also discovered a method to transmit key principles of Aikido in an easily absorbable manner to university students (who might only have four years to study with him), and that is why the Randori-no-kata has become the great learning tool it is, and one that informs understanding of the legacy Aikido techniques as retained and taught by way of the Koryu no Kata.
Looking at all of this in retrospect:-