[3] Kanai's father was a wealthy Japanese businessman and at the age of five he began his first stamp collection.

[4]: 186  At 13, he intensified his hobby and while in university founded two stamp collecting clubs.

Later, he became president of a number of companies[1] such as the Kanai Heavy Industry Co. At first, Kanai was a general stamp collector[1] but after World War II he specialised in the philately of Japan, Finland and the British colonies.

[1][6] Through philatelic contacts he became aware of and eventually owned a unique collection of the Red and Blue Mauritius "Post Office" stamps, when he procured a total of six pieces of 27 known copies of these valuable stamps, which was the largest ever owned by one person.

[10] He received many awards and worked most recently as Director of the Stamp Museum Kobe.