He chose the high school in Kumamoto because he wished to follow the path of Shinkuma Motoji, a renowned lawyer from his home village, Tatsugō.

He took a leading role in the formulation of a 10-year program to spur the development of Ōshima District, which passed the Diet in 1933 and went into operation in 1935.

He also helped build two ships that were operated between Kagoshima, the Tokara Islands and Amami Ōshima by Jittō Village.

[1] After World War II, Kanai was appointed as the 35th governor of Wakayama Prefecture in 1946 but was soon purged from the position for his affiliation with the Imperial Rule Assistance Association during the 21st General Election in 1942.

Exploiting his connections in the national political arena, Kanai took a leading role in the mainland side of the reversion movement.

[3] The Amami reversion movement reached its first peak before the conclusion of the Treaty of San Francisco on September 8, 1951, demonstrating that 99.8% of the islanders wanted an immediate return to Japan.

While the Amami Islanders considered Article 3 entirely unacceptable, an abrogation of it was virtually impossible because it required approval from all of the 49 countries that ratified the treaty.

In 1966, he published a memoir on the Amami reversion movement,[3] which he thought formed a precedent for Okinawa's return to Japan.