Yabu learned Shuri-te from Matsumura Sōkon and Ankō Itosu[1][2] and Tomari-te from Kōsaku Matsumora.

As a young man, Yabu learned Shuri-te from Matsumura Sōkon and Ankō Itosu.

[3] In those days, there was no distinction between different styles of karate, and Yabu did not call himself by the name of his school for the rest of his life.

[5] Following separation from the service, Yabu became a teacher at Okinawa Prefectural Normal School in 1906.

As a former soldier, Yabu has been credited with helping make Okinawan karate training more militaristic.

If so, this was probably part of the general militarization of Japanese athletics common during the early 20th century.