Serafall Leviathan

Serafall Leviathan, formerly known as Serafall Sitri, is the current Satan with the title of "Leviathan" and Sona's older sister.

Appearance
Serafall is a beautiful girl with long black hair tied in twin ponytails and violet eyes. She also has a child-like body (albeit with big breasts) and usually dresses in magical girl's clothing (from Magical Girl Milky Spiral Seven, the same outfit Mil-tan wears), magic wand and all, prompting Issei to coin her the nickname "Satan Girl" (魔王少女 MaŌ Shōjo).

Personality
Unlike her serious younger sister, Serafall has a child-like personality, which is evidenced when she calls her sister "Sona-chan" and "So-tan" and Sirzechs "Sirzechs-chan". Adding to her child-like personality is the fact that most of her lines end with a star. She also has a deep sister complex, and has a tendency to get her sister in embarrasing situations.

History
Serafall is the older sister of Sona Sitri and the oldest sibling of the Sitri Family. Some time before the start of the series, she was promoted to the Satan Leviathan.

Birth of the Breast Dragon Emperor
Serafall first appears in Volume 4 during the class observation day at Kuoh Academy to see her sister while getting attention from many photographers. Upon seeing her sister, she asked her why didn't she tell her about the class observation, claiming that she nearly attacked the Heavens out of shock of not being informed about the class observation. She and Sirzechs later attend the the meeting between the leaders of the three factions, which was attacked by the Khaos Brigade.

In Volume 5, she and the other Satans gather during the opening ceremony for the Young Devils Gathering and was unhappy at the fact that the elders of the noble families made fun of her sister. She along with the VIP from other faction are later shown to be viewing the Rating Game between Rias and Sona, feeling happy at the fact that her sister's servant, Genshirou Saji, is complimented.

The Heroic Oppai Dragon
In Volume 8, she participated in Issei and Rias' ceremony at the Ruins of Connection where she acted as Satan Pink and tested them on dancing.

In Volume 9, Serafall came to Kyoto for a peace talk with the Youkai, but this did not occur due to the Hero Faction kidnapping their leader. The peace talk, however, was successful after Issei, his friends and Sun Wukong managed to rescue Yasaka.

In Volume 12, Serafall goes to the front lines herself, being unable to bear with the the crisis faced by the Underworld, defeating one of the Bandersnatch with ease.

Powers & Abiities
Being a Satan, Serafall is a powerful Devil and specializes in using her family's trademark water-based magic, as well as being adept at using ice-based magic. She has a move named "Celsius Cross Trigger" (零と雫の霧雪(セルシウス・クロス・トリガー) Serushiusu Kurosu Torigā), which allows her to convert even the land itself into a world of ice, as shown when she froze up an entire region of the Underworld along with the Monsters created by Annihilation Maker with ease. Her sister Sona once stated that Serafall could destroy the nation of Japan several times over.

Trivia

 * Serafall has her own TV show in the Underworld called "Miracle☆Levia-tan" (ミラクル☆レヴィアたん Mirakuru☆Revia-tan), which has a rivalry with Oppai Dragon.
 * Serafall sees Gabriel as her biggest rival.