From Kirei Cake:
Possessing both flexibility and tenacity, Imomushi (Japanese for Caterpillar) is an assassin that does not kill anyone but those who are assigned to her. She seems to have had something happen between her and her older sister in the past, however.
A new spin-off story from the same author of Arachnid, this story looks at the inner workings of a top assassin within The Organization itself.
Note: In early 2014, serialization resumed with a new artist. The series had been on hiatus after the sudden passing of the previous artist in 2013.