Set in the fictitious city of Greater Tokyo Ward where people using the device "SCM" that can make others into slaves. In this world you can "borrow" and become a "slave" or "lend" and become a "master"? This work is the latest in the mystery-group image drama "Slave Ward" series by Shinichi Okada, with a cumulative circulation of over 3.6 million.

From MangaUpdates:A beast tamer without a familiar, Lock had been supporting his friends in an S Rank party until they finally decided to use him as a decoy and abandoned him. After a conversation with the Fenrir his party was attacking, it chose to serve him as his familiar. By using and expanding the [Mini Monster Garden], Lock gathers more and more familiars to form the strongest- and cutest- party ever. Behold, a fantasy where men and beasts go on adventures together.