Yubelluna is a voluptuous woman with long, wavy purple hair that falls all the way down her back and matching eyes. At the front, the right side of her hair falls over her breast and covers her right eye, while the left side falls near the top of her skirt.
Her attire is a dress consisting of a navy blue tunic top with gold accents and a pale blue skirt with open sides, black shoes and over matching thigh-high stockings with garter belts. The top reveals much of her cleavage, and is held with a gold choker with blue and red jewels. Over this, she wears a white overcoat with black and gold accents and matching pauldrons. For accessories, she wears a black headband with a red-orange jewel over her forehead to keep her long hair in place, and wields a staff-like scepter in battle. For cosmetics, she wears purple lipstick and nail polish, matching her eyes and hair.
In combat, Yubelluna is a cunning opponent but extremely submissive in Riser's presence.
Not much is revealed about her past, only that at one point in time, she was reincarnated as a Devil by Riser.
Yubelluna was introduced in Volume 2 when the Occult Research Club members met with Riser and his peerage. At the Rating Game match between Riser and Rias Gremory, she was sent to the front lines by Riser after Issei Hyoudou, Koneko Toujou and Akeno Himejima defeated Xuelan, Mira, and Ile and Nel, where she defeated Koneko while Koneko and Issei were careless. She then fought against Akeno in a one-on-one fight and won (albeit with the use of Phoenix Tears). Yubelluna then defeated Yuuto Kiba after Yuuto and Issei successfully defeated all of Riser's remaining peerage members with the combining of the Sword Birth enhanced by the power of Boosted Gear Gift, except for Ravel Phenex, leaving Rias with Issei and Asia Argento, before heading back to her master's side. When Issei appeared during Rias and Riser's fight, Yubelluna offered to take on Issei and Asia but was stopped by Riser, who wanted to clear things up and finish the battle.
In the Extra Life of DX.1, Yubelluna took part in her master's rematch against Rias. She faces off against Akeno who held a grudge towards Yubelluna for defeating her last time, as Akeno fights her with the full extent of her Fallen Angel Holy Lightning abilities. Later on, she is retired for losing her match with Akeno.
Powers & AbilitiesEditDemonic Power: As a Queen, Yubelluna possesses all the powers of a Knight, Rook, and Bishop thus giving her enhanced speed, strength, defense and magical power.
- Enhanced Strength and Defense: From the Rook trait of her Queen Piece, Yubelluna has strength and durability enhancement, giving her enhanced strength and defense.
- Enhanced Speed: From the Knight trait of her Queen piece, Yubelluna has speed enhancement, increasing her speed.
- Magic Talent: Due to the Bishop trait of her Queen Piece, Yubelluna is shown to be skilled in magic.
- Fire Magic: Yubelluna excels in fire magic. She uses powerful fire magic from her wand or hand that looks like a bomb explosion when hitting the target.  Her fire magic is shown to be powerful enough to eliminate both Koneko and Yuuto in one attack.
- Sealing Magic: Yubelluna has some skill in sealing magic, as she was able to use it to seal and restrict Asia's movements.
Flight: Being a Devil, Yubelluna can fly using her wings, just like all other devils..
- In the anime, Yubelluna was used by Riser to make Issei jealous, while in the manga and light novels, Riser uses Ile and Nel instead.
- Yubelluna dislikes her nickname because of its bad taste.
- In the anime, Yubelluna was shown to be able to fly without her Devil wings as opposed to the Light Novels where she had to use her Devil wings for flight.