Shion emerged as one of the few survivors following the genocide of her Ogre tribe. Leading her remaining brethren through the Jura Forest, she mistakenly attacked Rimuru Tempest, believing him linked to their enemies. After Rimuru overpowered them and revealed their error, Shion and the Ogres pledged allegiance. Rimuru named them, triggering their evolution into Kijin. Shion immediately declared herself Rimuru's "first secretary," though her duties leaned heavily towards bodyguarding, with Shuna managing most secretarial responsibilities. As an Ogre, Shion bore a wild appearance: a thick black forehead horn, light purple ponytail, purple-tinted skin, and a noticeably curvaceous form. She wore a brown robe revealing cleavage and a necklace with green and tooth-like stones. Her evolution into a Kijin, coinciding with Rimuru's ascension to Demon Lord, refined her features: the horn narrowed, her skin lost its purple hue, and her hair lengthened, reaching 170 centimeters. She adopted a formal purple suit over a light green shirt, typically leaving the jacket open. A later, unique evolution transformed her into an "Evil Oni" or "Wicked Oni," diverging from the typical Mystic Oni path of her kin, attributed to her battle-focused nature and unique resurrection circumstances. Shion's personality blends fierce loyalty with profound clumsiness and emotional volatility. Her devotion to Rimuru is intense, carrying reverential and romantic undertones. This manifests as extreme protectiveness and jealousy towards anyone showing Rimuru interest, even defying Shuna during displays of affection. Despite her self-assigned secretary title, Shion lacks secretarial aptitude, frequently making errors like misremembering names. Early insecurities centered on abandonment fears, fueling rivalry with others. Post-resurrection, she gained greater self-assurance, shifting focus from competition to surpassing her own limits. Her impulsiveness often drives her towards violent solutions, though moments of unexpected strategic thinking emerged after resurrection, such as taming Dagruel's sons and turning them into students. Shion is notoriously inept at domestic tasks; her cooking produces toxic, sentient substances, necessitating Rimuru's intervention via gifting standard knives. Alcohol worsens her emotional instability, causing loss of restraint and tearful outbursts. She exhibits pride in Rimuru's achievements as her own and commands leadership over a personal army. A pivotal moment occurred when Shion was killed during an attack on Tempest. Rimuru resurrected her using soul energy harvested from demons during his own evolution to Demon Lord. This act deepened her connection to Rimuru, granting enhanced intuition and fragments of his computational power, enabling her to deduce truths from scant information. The resurrection solidified her loyalty and diminished her insecurities about replacement. She evolved into an Evil Oni, gaining the title "The Immortal" and abilities including Pain Nullification, Status Change Nullification, and resistances to physical, spiritual, and holy attacks. Within Tempest's hierarchy, Shion holds multiple leadership positions: a member of the Twelve Guardian Lords and Rimuru's "Big Four," commanding her personal army. Her formidable combat prowess leverages immense strength and regeneration. In OAD episodes featuring Rimuru's teaching activities, she supports his endeavors in human nations like Ingrassia. Across all media, her narrative traces growth from a vengeful Ogre survivor to a complex leader whose strengths and flaws contribute to Tempest's foundation.