Shokugyo Koroshiya.

Summary

Enter "Shokugyou Koroshiya," an underground website that allows hired killers to bid for the lowest amount to take the paying job that they want. Kumo, the top killer of the agency must keep killing to keep a memory hidden. While he continues to kill, along with Megumi the Mantis, and KEI, the 14-year-old owner of the website, what dangers await him and the rest of the team...? (Source: MU)