Marry no Kakuu Sekai (chapter)

Kagerou Days 9.5 Mary's Fictional World (カゲロウデイズ9.5マリーの架空世界) is the extra chapter of the Kagerou Days Manga featured in the Mekakucity Records booklet.

Summary
Mary dreams about Dark Konoha in the act of killing Seto after he already got rid of everyone else. She attempts to use her powers of "combining" against Konoha to stop him and turns him into stone, not wanting to live in a world without her friends. Eventually she wakes up from her dream, and finds everyone safe and alive in the Mekakushi Dan hideout.