Seiseki Abe (阿部醒石, Abe Seiseki) (April 26, 1915 – May 18, 2011, Osaka, Japan) was a Japanese shodo and aikido teacher who had a unique relationship with aikido founder Morihei Ueshiba, being both his student in aikido and his teacher in calligraphy.
Source: “Seiseki Abe”, English Wikipedia (CC BY-SA 4.0), excerpt