text: Al-Zarqawi says Japan offered ransom for Koda; gov #39;t says it didn #39; &lt;b&gt;...&lt;/b&gt; BAGHDAD - Abu Musab al-Zarqawi, who heads a group of Islamic extremists affiliated with the al-Qaida network, said in a statement posted on a website Tuesday that his group is responsible for the murder of Japanese hostage Shosei Koda, while repeating 