https://sega-pspdl.jp/pc/dlmission/

"Gemaga Dungeon"
Single player, story mode
In collaboration with Gemaga, this mission features quantities of monsters like you've never seen before! The object here is to defeat 2,000 of them. Think you can do it?

This is the mission that was mentioned a while back where by meeting the goal of 2,000 enemies killed, you'll earn the wand Bukra Gemaga.