Board Thread:Questions and Answers/@comment-31725345-20170721154754/@comment-78.194.252.210-20170922162232

And Shiki can"t exactly "kill anything". As proofed by Melty Blood, she is unable to kill some things too great above herself (gods notably), as seen when she face Arc in Melty Blood and doens't see her lines.

Also, she depend of Akasha, however we know from  a certain time that Akasha herself was made by primeval goddesses of life and earth (like Gaia herself in fact), placing her behind all of it.