Ok, after checking the source code for the site, I am tending to think that this is just an error. Here is a bit of the code from the main site, where the "?" appears.
" <div class="mainbox" id="update">
<iframe frameborder="0" marginheight="0" marginwidth="0" scrolling="no" src="pshowupinfo.php"></iframe>
Essentially this just says Reference a server address to get the content for this little box. I.E., it references this address: http://www.konami.jp/gs/game/genso/pshowupinfoall.php
In order to get its content. Clicking on it reveals no "?" on the .php site. Now, here is the code from the .php address:
<div class="main" id="updatefull">
<a href="http://www.konami.jp/akiwari/" target="_top">人気タイトルをベストプライスで！！「秋割」実施中！ </a>
This shows us the Second Header and the first link on the page. There are no errors here, and I see nothing that could generate a random "?" in the box on the main page. However, this "?" character sometimes disappears and reappears when you refresh the page. So, there is
probably a random, rouge "?" somewhere in the source code that pops up on occasion. I don't know though, I've never written anything more than HTML basic, so this is a bit above my head.