The Shadow

The Shadow is a painting dropped by the Harmonics Clone. It depicts a female player with Yoraiz0r's Outfit and Skirt on with silver hair and swords in place of her hands walking through a large white room fighting off odd black figures.

Notes/Trivia
This is a reference to an episode of Angel Beats! in which Kanade Tachibana uses Hand Sonic to fight off the Shadow. I won't say which one due to it being a spoiler.