In middle school, Nankoku developed an interest in calligraphy. During his second year, he began browsing through his father’s library on his own, voraciously copying at random books of classical ink rubbings. Tenrai left his child to copy them freely without interference or compulsion, but taught Nankoku classical techniques of writing and commented his works.
Tenrai could not fulfill the beautiful kai-sho (character) in the Tang dynasty age by the writing method ‘ kai-wan-ho’ (turn-arm-method) of his teacher Meikaku Kusakabe, so he studied intensively the classical Chinese calligraphy. As a result, he discovered a new method ‘ fu-gyo-ho’ ( downward-upward-method, the old brush method) and continued to make the nationwide journey for the purpose of spreading this method. Also he envisioned to found a general research institute of calligraphy with collections of many ink rubbings and ancient calligraphy books.
In 1927 at Yoyogi-Sanya, Tenrai Hidai established the long-waited Shogakuin to revive and promote a pure form of calligraphy based on the old brush method. Nankoku had free access to Shogakuin and carried out many books of classical calligraphy. The institute attracted great numbers of young students. Sokyu Ueda, Otei Kaneko, Suiho Kuwahara, Yukei Teshima, Gakyu Osawa, Seiko Ishida and so on gathered in Shogakuin , who were leaders of new calligraphy in postwar Japan.
In later years, Nankoku remembered: Someone asked Tenrai, “ Sho is the art of writing characters. If Sho is apart from the character, can Sho be composed ? ” Tenrai instantaneously replied, “ Of course, yes. If Sho cannot be composed, Sho doesn’t exist as art.” Later this is relevant to Tenrai’s word ‘ Shou ‘ (no character, ink form by brushstrokes ) which artists of abstract calligraphy or ink form were heard of.