Morihei Ueshiba (植芝 盛平 Ueshiba Morihei – December 14, 1883 – April 26, 1969) was a martial arts master and the founder of the martial art Aikido. He is often referred to as “Kaiso (開祖?)” or “Ōsensei,” meaning “Great Teacher.”

The son of a landowner from Tanabe, Ueshiba studied a wide variety of martial arts and served in the Japanese Army during the Russo-Japanese War. After his discharge from the army, he moved to Hokkaido, where he met and trained with Takeda Sokaku, the founder of Daitō-ryū aiki-jūjutsu. Leaving Hokkaido in 1919, Ueshiba joined a branch of the Ōmoto-kyō movement in Ayabe, where he worked as a martial arts instructor and opened his first school. In 1924, he accompanied the movement’s leader, Onisaburo Deguchi, on a mission to Mongolia, where they were captured by Chinese troops and sent back to Japan. The following year, he experienced a profound spiritual awakening, stating that “a golden spirit sprang from the ground, enveloped my body in a luminous veil, and transformed my own body into gold.” After this experience, his martial arts skills seem to have developed rapidly.

Ueshiba moved to Tokyo in 1926, where he founded the Aikikai Hombu dojo. At the end of World War II, the dojo closed, but Ueshiba continued to teach at another dojo he had founded in Iwama. From the end of the war through the 1960s, he strove to spread the art of Aikido throughout Japan and abroad.