The other investor who owns 30% is not asking for this. I own 50% equity. I have been taking care of the day to day runnings of the business as CEO and Founder.
It hard to give you solid advice on just the informaiton provided, but,clearly, something triggered this request and it appears fundamental trust might be at the root of it. If he/she has been an investor for a period of time, how well have you kept them informed about the business' progress? Have you sent out periodic financial statements? Have you engaged in periodic review meetings or dialogues with this investor (or the other for that matter)? If this is a new investment (with the last 90 days or so), have you executed an agreement with them? Were there any stipulations in that regarding the frequency or depth of reporting to shareholders? And, finally, (and this is my guess) is this investor one who has never done this before - i.e., put his/her money at risk? That may be the issue. Hope this helps you sort it out.