Silver Wings

The Silver Wings were a man and woman adventurer duo of great renown who were ultimately killed by the demon Orthos.

Appearance
The male member of the Silver Wings was a man of above-average build with medium-long hair. The female member was also of above-average build with ragged neck-length hair. Both of them wore typical traveler's clothing and fur-lined coats, similar to the dwarven-made coats worn by the hobgoblins of Rimuru's village in their early days.

History
During Shizue Izawa's days as a traveling hero, the Silver Wings were among the first of the many adventurers summoned to the kingdom of Filtwood under the pretense of slaying a demon threatening the kingdom. Supposedly, this demon had been slain in the distant past by a hero known as Orthos but had recently been revived.

In reality, the story was all a fabrication-- Orthos himself was the demon, and secretly controlled the kingdom while posing as one of its knights. He had been using the demon slaying request as a ruse to lure in powerful adventurers so that he could kill them, not only to consume their souls and gain more power from them, but also to eliminate said adventurers as potential threats to his continued rule.

The Silver Wings discovered the true identity of the demon too late. They failed to stop him, and were both mortally wounded by Orthos in their battle. However, they managed to escape before he could finish them off and take their souls.

Not long after they had made it out of Filtwood's castle and into the nearby woods, the male Silver Wing soon succumbed to his injuries and died. The surviving female Silver Wing was similarly on the verge of death. However, driven by rage and a thirst for vengeance upon Orthos, she used her own blood to draw a demon summoning circle on the ground, cursing Orthos all the while. Subsequently, she managed to summon the Primordial Demon known by the epithet Noir (the one who would later be known as Diablo after Rimuru summoned him). She begged him to kill Orthos and his human puppets, offering her and her partner's souls as payment with her last breath before falling dead on the ground. Amused and delighted by her dying emotions, Noir agreed to her request and took the Silver Wings' souls, saying that while they were an insufficient payment, he would take the lives of their targets to make up the difference. Upon sealing the contract with them, their bodies turned to ashes in the wind, leaving only their clothes behind.

Their garments were later discovered and reported to be all that was left of them by Orthos' human puppet minister when he addressed the other adventurers (including Shizue) who had responded to the phony demon-slaying quest.