Takeda Sogaku was responsible for bringing Daitoryu Aikijujitsu into the 20th Century. In addition to being the Master of Daito ryu Aikijujitsu, he also studied Ono Ha Itto Ryu, and Jiki Shinkage Ryu. His skills as a martial artist were also bolstered by his ability with other classical Japanese weapons. Takeda Sensei posessed the Bugei Ju Happan, which signified mastery in eighteen weapons. Takeda also studied Hozoin Sojutsu, a classical form of spear fighting. Takeda taught Daitoryu from the beginning of the twentieth century until his death in 1943. Although his son Tokimune Takeda became the Headmaster of Daitoryu Aikijujitsu when Sogaku died, is understood that Sogaku's top students were Kodo Horikawa, Yukiyoshi Sagawa, and Takuma Hisa.

Horikawa Kodo originally studied with his father, but later was taught by Takeda Sogaku. While in Hokkaido, one of Japan's northern islands, Sogaku lived with Horikawa's family. Learning in small lessons four or five times daily, Horikawa Kodo mastered Daitoryu and achieved a supreme level of Aiki techniques, which are the very heart and soul of Daitoryu Aikijujitsu.

Horikawa Sensei received the entire system of Daitoryu from Takeda Sogaku and was awarded every rank and honor, including the Menkyo Kaiden.

Upon the death of his teacher, in accordance with Japanese martial tradition, Horikawa began the Daitoryu Aikijujitsu Kodokai. In 1974, Horikawa Sensei received the Eisei Mejin (Martial Genius), the highest award given by Japanese Government. His Honor Ishida Kazusoto, who was at that time the President of the Japanese Supreme Court, oversaw this process.

Okamoto Seigo entered the dojo of Horikawa Sensei at the age of 38. Training 5 nights per week for many years, Okamoto slowly became the most senior of the students in the dojo as was teaching many classes per week under the guidance of Horikawa Sensei.

Okamoto Seigo was the first of Kodo's students to receive 7th Dan. Okamoto Soshi received the Shihan, or Masters License in 1978. Adhering to Japanese martial tradition, Okamoto founded Daito-ryu Aikijujitsu Roppokai in 1980, the year Kodo sensei died.

In 1985, Okamoto founded the first foreign branch of the Roppokai in Denmark. In 1997, Howard Popkin traveled to Tokyo, Japan to train with Okamoto Sensei and was given permission to form the New York Roppokai.