Kenwa Mabuni
By 1928, Ōtsuka was an assistant instructor in Funakoshi's school. He also trained under Chōki Motobu and Kenwa Mabuni, and studied kobudo, around this time. Ōtsuka began to have philosophical disagreements with Funakoshi, and the two men parted ways in the early 1930s. This may have come, in part, from his decision to train with Motobu. Funakoshi's karate emphasized "kata", a series of movements and techniques linked by the fighting principles. Funakoshi did not believe that sparring was necessary for realistic training. Motobu, however, emphasized the necessity of free application, and created a series of two-person "kumite" called "yakusoku kumite".