Pleiades of the Azure Sky

The are a group of six Holy Knights who serve under Denzel Liones, assistant to the Great Holy Knight. They were assigned to guard the borders of the kingdom by the two Great Holy Knights, Dreyfus and Hendrickson.

Post-Infiltration arc
During the award ceremony held in honor for the Seven Deadly Sins minus Ban and King who were still at the new Fairy King's Forest and Escanor still missing, three of the Pleiades of the Azure Sky: Death Pierce, Dogget and Wayeo stepped forward after Meliodas called out to the Holy Knights who complained and talked behind his back to have a voice in the matter to which the Dragon's Sin of Wrath was pleased of their honesty.

Death Pierce politely requested to King Baltra Liones for a battle against the Seven Deadly Sins in proof to see if the legendary order of knights that saved Liones from Hendrickson are really strong as they thought. The king reluctantly granted his request as Dogget volunteers to face Meliodas.

After Dogget easily lost to Meliodas, Death Pierce concludes that they've seen enough and leaves the scene while revealing that a friend closest to Dogget had lost his life during a battle against Hendrickson while they were away from the kingdom at that time.

Ravens arc
When Fraudrin of the Ten Commandments arrived at a town somewhere in the borders of Liones, two members of the Pleiades of the Azure Sky: Arden and Deldrey anticipated his arrival and proceeded to carry out Denzel's strategy of capturing Fraudrin. Wayeo joined them in the ensuing battle against him, and the trio were successful in their efforts.

Trivia

 * The Pleiades led by Denzel can be regarded as a "brother" group of the sins. There are seven sins, and the name of Pleiades hails from the seven daughters of Pleione who became immortalized as stars.
 * While The Pleiades' greatest strength lays in teamwork, they are the contrast of the Sin who's strength lies in their lack of teamwork.
 * Likewise, one group works directly under the king, the other under the king's brother.
 * And in constrast to another, the seven sins are biblical vices which lead to death and destruction of grace and purity when broken, while the seven sisters were known for their beauty and grace.
 * Incidentally, the mythical Pleiades' father was Atlas who carries the burden of the world on his shoulders, while the leader Denzel has spent the past 10 years to research how to defend the world from the resurrection of the Ten Commandments.

Seis Estrellas del Cielo Azul