Conversation so far:
What two groups combined to form the Kanjani Eight?
It was a combination of Kansai Johnny's Jr. of the Junior golden age and the newly popular V. West (Five West).
Why did they combine?
Was this group successful?
Thirty three of thirty six singles have placed at number-one on the Oricon singles chart and they have sold a total of 17 million album copies in Japan.

Question: What else is significant about the combination?
Self-contained rewrite: What else is significant about the combination of the groups leading to the Kanjani Eight?