One day, security officer Asahina is appointed to Security #4. Skills are required because it is the most dangerous of security roles. Asahina used to be a police officer but retired due to a "setback" and joined the security company Guard Keepers. A middle-aged man called Ishimaru is designated his partner. Ishimaru was once a company president but became a security officer and is labelled "coward" as a result of his excessively cautious personality. Although the two of them complain about each other, their boss Ikeyama seems to have some agenda and does nothing but give meaningful smiles while their company president has reservations about this pairing. Despite their conflicts, Asahina and Ishimaru have to personally protect people in all sorts situations.