We have received the following email. 
UPDATE: Basically we received a total of 5 emails from Attributor who claimed to be an authorized agent of Shueisha and tell us to remove few manga chapters (listed in page 2).
What are you going to do?
For now, we will stay on the safe side. We will comply as and when necessary and removed the content as per requested. Until there is a better solution, we will continue to comply. Sorry for the inconvenience.
Thanks for the support, and we hope that you still continue to support us.
UPDATE (email dated 01/12/2011).
Received another 2 emails. More list coming (page 2).
[email-start]
Subject: This is a verified DMCA Removal Request from Shueisha - Manga
From: remedies@attributor.com
Reply-To: remedies@attributor.com
To: inaruto.net@gmail.com
*** Sent via Email - DMCA Notice of Copyright Infringement ***
Dear Sir/Madam,
I certify under penalty of perjury, that I am an agent authorized to act on behalf of the owner of the intellectual property rights and that the information contained in this notice is accurate.
I have a good faith belief that the page or material listed below is not authorized by law for use by the individual(s) associated with the identified page listed below or their agents and therefore infringes the copyright owner's rights.
I HEREBY DEMAND THAT YOU ACT EXPEDITIOUSLY TO REMOVE OR DISABLE ACCESS TO THE PAGE OR MATERIAL CLAIMED TO BE INFRINGING.
This notice is sent pursuant to the Digital Millennium Copyright Act (DMCA), the European Union's Directive on the Harmonisation of Certain Aspects of Copyright and Related Rights in the Information Society (2001/29/EC), and/or other laws and regulations relevant in European Union member states or other jurisdictions.
My contact information is as follows:
Organization name: Attributor Corporation as agent for Shueisha - Manga
Email: remedies@attributor.com
Phone: 650-340-9601
Mailing address:
119 South B Street
Suite A,
San Mateo, CA 94401
My electronic signature follows:
Sincerely,
/Steve Pearson/
Steve Pearson
Attributor, Inc.
*** INFRINGING PAGE OR MATERIAL ***
Infringing page/material that I demand be disabled or removed in consideration of the above:
Original Work: .... (list continued to next page)
[...........end-of-email]