If you are selling software products in Japan, you might need a helpdesk tool to keep track of your clients' questions and problems. I performed an evaluation of 10 helpdesk software solutions and here are the results. I first selected 30 tools (including bug trackers), and restricted my choice to ten tools that are open source, actively maintained, and localized in Japanese.
In the QSOS spirit, I defined criterions and filled the matrix. I gave a weight to each criterion according to what is important to me, but using this OpenOffice spreadsheet you can input your own weighings according to what is important for your company.
My winners are SiT! and GLPI.
But OTRS would be above if it were officially localized in Japanese.