Ayu most definitely does NOT own a large amount of shares in Avex.
Max Matsuura, the founder and CEO of Avex owns only 4.89% of the shares in his own company, so even if Ayu does own some shares in Avex it can't be a whole lot.
This is public information on Avex Group's website, and you can find it here:
http://www.avex.co.jp/e_site/ir/stoc...k_bond_03.html