Soul Shadow

Anime
Soul Shadow is not a monster per-se but rather an illusion of an apparition similar in appearance to Nephrite even though some specify that it is itself a part of him. Similar to the youma Regulus, Soul Shadow was not involved in any energy-absorbing plots but was used by its master, Nephrite to rob the visiting Princess D from the Diamond Kingdom, the royal treasure she is set to inherit at a reception inside the Diamond Kingdom embassy.

Both Luna and Queen Beryl speculated that the royal treasure could be the legendary Silver Crystal with Luna adding that Princess D may be the Moon Princess that she is searching for. Consequently, both Luna and Queen Beryl of them assigned their subordinates to look into this matter.

Nephrite, who snatches this assignment from Zoisite, notices Naru Osaka inside the embassy. Given that her feelings for his alter ego, Masato Sanjouin, would make her vulnerable, Nephrite flattered her before implanting his youma inside of her and taking complete control of her mind. Nephrite then used her as a "middleman" to enter the princess's quarters and "pass" the youma onto her, so the latter could steal the treasure.

The power of the youma was controlled by the concentration of Nephrite. What was supposed to be an easy assignment was complicated by Usagi Tsukino (who snuck into the embassy with her disguise pen), where she was alerted by Luna of the theft of the treasure and in her botched attempt at stopping the possessed princess from handing it to Nephrite, slips and falls from the balcony. Tuxedo Mask who catches her by the hand is bumped from behind by the possessed princess. "He doesn't fall, but Luna sees what is happening and attacks the princess".

Consequently, Nephrite's concentration in the youma was disrupted by the intervention of Sailor Mars and Sailor Mercury who prevent Nephrite from finishing off Tuxedo Mask and Usagi Tsukino. When he retreats to block away from the embassy, Nephrite uses his concentration via his evil crest to reawaken his youma who was still inside the body of Princess D. The possessed Princess D was able to use the power of the youma to blast dark energy at the guests inside the embassy making the fall to the ground unconscious as she again uses the power of the youma to leap off the embassy balcony and float to the ground.

“She tries again to deliver the treasure to Nephrite, but Sailor Mars exorcises," the youma from the possessed Princess D using her anti evil scroll attack . The youma floats out of her body and attacks Sailor Mars, Sailor Mercury and Sailor Moon with the a blast of dark energy. Sailor Mercury uses her Sabão Spray attack against the dark energy attack causing it to stop. This gave Sailor Moon the opportunity to destroy the youma with her Moon Tiara.

Manga
In Act 4, Soul Shadow was actually a female youma disguised as an interpreter for Princess D. It took possession of the Princess and tried to steal the the treasure, which it believed to be the Silver Crystal. Once it revealed its form, it was immune to Sailor Mars's attacks. Sailor Moon attempted to use her tiara to destroy it, but realized it was destroyed in the battle against Jadiete. Suddenly a new tiara appeared on and the youma is destroyed by Sailor Moon's Moon Twilight Flash attack, produced by the new tiara.

Crystal
Nephrite disguises himself as a female attendant for Princess D. Once she and Nephrite are alone in the room with the treasure, Nephrite begins to attack her, but is interrupted by Sailor Mercury and Sailor Mars. He sends his shadow into Princess D, possessing her to try and escape with the treasure. When the guards try to stop her, she engulfs the room in darkness. Once confronted by the Sailor Senshi, the shadow emerges from the princess, revealing Nephrite's appearance. Sailor Mars tries to use her powers to destroy it but it is unaffected. Sailor Moon, using her new tiara, blasts the shadow with light reflected from the moon and it is destroyed.

Trivia

 * Soul Shadow's death can be seen in the opening sequence of the English dub.

Gallery
Soul Shadow Soul Shadow