Empressmon is an Angel Digimon whose English name is derived from Empress, which signifying her nobility and her evitable rule over the Digital World, while her Japanese name and design are derived from woman, more specifically as the first woman, Eve in the Book of Genesis in the Hebrew Bible. She would later be known as being one of the founders of the Royal Family, most notably as the Queen of the Digital World. Her husband is Emperormon, who would later be known as King Royalmon and her eventual children are Valentinemon, Sirenmon, Metaldramon/Signamon and Princessmon.
She is one of the first Digimon created by God, along with Emperormon being the equivalent to Adam and Eve in the Book of Genesis in the Hebrew Bible. Her original home is located far near Yggdrasill with chambers connecting it to the rest of the Digital World, giving her access to the Royal Knights, Digimon Sovereigns, Ten Legendary Warriors, Celestial Digimon and the Olympos XII and a field rivaling that of the Garden of Eden. Alongside Emperormon, she was appointed as Duchess of the Digital World after a wide consensus made by Royal Knights, Celestial Digimon and the Olympos XII. is greatly respected and feared among many Digimon. She's often compared to her twin brother, Valentinemon, in terms of leadership, power, and appearance. When her parents were dethroned by the Celestial Digimon, Sirenmon and her siblings were forced to retreat to the Dark Area, where they were looked after by the Seven Great Demon Lords until they were reunited with their parents; also due to the allegiance the Royal Family had with them. She is also known as one of the most beautiful Digimon, rivaling that of her younger sister Princessmon. Due to the hierarchy of the Royal Family, Sirenmon also has command over many Demon Lord, Devil, and Fallen Angel Digimon; she also has command over the Elemental Gods, with the exception of her brother. Sirenmon is the only one of the Royal Family to be directly Cetusmon, the God of Water. While the army she controls are mostly the "Nightmare Soldiers", she also has power over the "Deep Savers". Like her siblings, she too resembles a human teenager, with the exception of her winged fins and mermaid-like tail. Like her siblings, she can retract her winged fins and tail inside her body. She also has the ability to transform her tail into two human-like legs and shift her tail's position as well. Her outfit resembles that of the one worn by Dark Phoenix in the X-Men comics.
- Possession – Like her family, Sirenmon is able to merge her body and overshadow or otherwise control another life form. While she has some strength of her own, Sirenmon's combat abilities are best suited to exploiting the full potential of a host body. It appears that when she has chosen a permanent host, she begins to alter the host's appearance to mirror her own (as evidenced by the appearance of Yoshino). After possessing a host, Sirenmon combines their power with her own. She also gains the ability to assimilate the techniques of those who she has possessed. Sirenmon uses this to take control of. Sirenmon uses this to take control of Sora Takenouchi and Yoshino "Yoshi" Fujieda.
- Death Beam - She extends her right arm and fires a small, thin, very fast, and concentrated laser-like beam from either her index finger or her tail, which barrels down and pierces through an opponent.
- Power Up - She has the power to suppress and increase her power.
- Telekinesis – She can lift or move large objects through the air and blow up objects as big as mountains with only her mind.
- Barrage Death Beam - A rapid-fire version of the Death Beam technique.
- Explosive Wave – She bursts out energy from all over her body in order to repel the opponents around her.
- Super Explosive Wave – A stronger version of the Explosive Wave, she releases a gigantic wave of energy from her body, causing a huge amount of destruction.
- Finger Beam - She holds out her index finger and releases an energy beam from her fingertips.
- Scatter Finger Beam - She leans forward and points all five fingers of her right or left hand, then she charges up five small golden-yellow energy spheres each on the tip of each finger and finally fires the energy spheres inflicting a great deal of damage.
- Continuous Energy Bullets or Continuous Energy Waves - She fires many energy waves from a single hand at once at a very rapid rate, which causes a lightning speed effect.
- Magic Materialization – Used to create clothes for herself.
- Shape-shifting – Her and her family have the power to shape-shift into any human and Digimon they have come into contact with.
- Eye Lasers – A thin laser-like beam is shot from both of her eyes.
- Telepathy – She has the ability to channel one's thoughts to another being.