[*Petit*]

"Avex" consists of many companies. She doesen't have any position on the board of avex group (probably too busy!). I couldn't find any similar information on any of the subsidiaries. I don't think her contract with avex is available to the general public, but it may or may not include various clauses that allow her to get stocks or other ways giving her more influence on the company.

Avex group Inc is listed on the Tokyo stock exchange and if the japanese regulations are anything like most western countries', a shareholder holding more than a certain % of the stocks can easily be found on a list of shareholder, if you're really interested. I don't think she'd hold that amount of stocks in her own name though... (maybe through holding company) I don't know anything about her personal finances. I'm sure you could find more information through a japense search or through japanese financial news.