Information in the game database is updated periodically. Below, you'll find that information compiled as pertains to Level 5. The company may be involved as a publisher, developer or both.
Dragon Quest IX: Sentinels of the Starry Skies [July 11, 2010]
Professor Layton and the Curious Village [February 10, 2008]
Professor Layton and the Diabolical Box [August 24, 2009]
Professor Layton and the Last Specter [October 16, 2011]
Professor Layton and the Unwound Future [September 12, 2010]
Jeanne d'Arc 
There are numerous companies in the industry, and their names change like the weather. The information above is not particular about the finer details. Acquisitions are common, so companies with no recent listings may still be developing games under a new name. For example, DMA Design currently has a Rockstar name. Do you know of a title that is not listed above but should be? Be sure and let a staff member know. You can contact staff if you click here.