Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
2004 in Deep
Table title:
Events list
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > # </th><th colspan=1 rowspan=1 > Event title </th><th colspan=1 rowspan=1 > Date </th><th colspan=1 rowspan=1 > Arena </th><th colspan=1 rowspan=1 > Location </th></tr>
<tr> <td colspan=1 rowspan=1 > 26 </td><td colspan=1 rowspan=1 > Deep: 17th Impact </td><td colspan=1 rowspan=1 > December 18, 2004 </td><td colspan=1 rowspan=1 > Differ Ariake </td><td colspan=1 rowspan=1 > Tokyo </td></tr>
<tr> <td colspan=1 rowspan=1 > 25 </td><td colspan=1 rowspan=1 > Deep: clubDeep Osaka </td><td colspan=1 rowspan=1 > November 28, 2004 </td><td colspan=1 rowspan=1 > Delfin Arena </td><td colspan=1 rowspan=1 > Osaka </td></tr>
<tr> <td colspan=1 rowspan=1 > 24 </td><td colspan=1 rowspan=1 > Deep: 16th Impact </td><td colspan=1 rowspan=1 > October 30, 2004 </td><td colspan=1 rowspan=1 > Korakuen Hall </td><td colspan=1 rowspan=1 > Tokyo </td></tr>
<tr> <td colspan=1 rowspan=1 > 23 </td><td colspan=1 rowspan=1 > Deep: clubDeep Toyama: Barbarian Festival 1 </td><td colspan=1 rowspan=1 > October 24, 2004 </td><td colspan=1 rowspan=1 > Toyama Event Plaza </td><td colspan=1 rowspan=1 > Toyama </td></tr>
<tr> <td colspan=1 rowspan=1 > 22 </td><td colspan=1 rowspan=1 > Deep: Chonan Festival </td><td colspan=1 rowspan=1 > October 3, 2004 </td><td colspan=1 rowspan=1 > Mikawa Town Gymnasium </td><td colspan=1 rowspan=1 > Mikawa </td></tr>
<tr> <td colspan=1 rowspan=1 > 21 </td><td class="highlighted"  colspan=1 rowspan=1 > Deep: 15th Impact </td><td class="highlighted"  colspan=1 rowspan=1 > July 3, 2004 </td><td class="highlighted"  colspan=1 rowspan=1 > Differ Ariake </td><td class="highlighted"  colspan=1 rowspan=1 > Tokyo </td></tr>
<tr> <td colspan=1 rowspan=1 > 20 </td><td colspan=1 rowspan=1 > Deep: 14th Impact </td><td colspan=1 rowspan=1 > April 18, 2004 </td><td colspan=1 rowspan=1 > Umeda Stella Hall </td><td colspan=1 rowspan=1 > Osaka </td></tr>
<tr> <td colspan=1 rowspan=1 > 19 </td><td colspan=1 rowspan=1 > Deep: clubDeep Fukuoka: Team Roken Festival </td><td colspan=1 rowspan=1 > March 20, 2004 </td><td colspan=1 rowspan=1 > TNC Broadcast Paveria Hall </td><td colspan=1 rowspan=1 > Fukuoka </td></tr>
<tr> <td colspan=1 rowspan=1 > 18 </td><td colspan=1 rowspan=1 > Deep: 13th Impact </td><td colspan=1 rowspan=1 > January 22, 2004 </td><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Tokyo </td></tr>
</table>
Question:
What is Deep: 15th Impact?
Answer:
Deep: 15th Impact was an event held on July 3, 2004, at Differ Ariake in Tokyo.