Сазекс — гарний молодий чоловік, який має зовнішність двадцятирічної людини з волоссям, що дістає до плечей, багряного кольору і блакитними очима, які він успадкував від батька. Іссей описує його, як чоловічій варіант Ріас.
У своїй справжній формі, він перетворюється на чисту Силу Руйнування, яка має людський силует та багряну ауру.
Як Ґреморі, Сазекс є дуже доброю людиною, яка піклується про інших та вважає за краще вирішити конфлікт за допомогою переговорів, а не битви. Сазекс має доволі спокійний темперамент, через що робить всі справи у своєму невимушеному темпі, за що часто карається Грейфією. Взагалі, достатньо лише згадати ім'я Грейфії, щоб вимусити його просити пробачення та діяти інакше. Втім, у Сазекса є і серйозна сторона, яку він показав під час протистояння з Крузереєм Асмодеєм та Аїдом.
Sirzechs is considered as a siscon because of his deep love for his younger sister, Rias Gremory, and as an overprotective and loving father for his son Milicas Gremory. Sirzechs also has a childish and playful side, shown when he deeply enjoyed posing as Satan Red while playing with his son Milicas, but then becoming upset over his son choosing Oppai Dragon over Satan Red acting in a rather childish manner.
Sirzechs is revealed to have a perverted side which is directed solely on Grayfia, as he stated to Issei he is free of distraction when he gropes his wife's breasts.
Sirzechs was originally the intended heir of the House of Gremory. He is also the childhood friend and rival of Ajuka Beelzebub, both being extremely powerful. In the past there was a quarrel between the Old Satan faction, who wanted to continue the War against Angels and Fallen Angels, and the Anti-Satan faction, who wanted to prevent this for the sake of the Devils, which Sirzechs was part of. Sirzechs, at the time, was an ace of the Anti-Satan faction alongside Ajuka and was even called a Hero. The result of the quarrel was the fleeing of the Satan faction to the end of the Underworld, and the creation of the current Devil society. It was also during that time that Sirzechs met Grayfia and fell in love with her. They would meet in secret during the Devil Civil War. The two of them eventually married each other after the end of the conflict between the Old Satan Faction and the Anti Satan Faction.
Sirzechs made his first appearance in Volume 2 during Rias' engagement party, where he indirectly (but purposely) helped break off her engagement with Riser Phenex.
In Volume 4, Sirzechs went to the Kuoh Academy along with his father for Rias' class observation day. Later, he and Serafall Leviathan were sent as the representatives of the Devils during the peace talk between the three factions, which was invaded by the Khaos Brigade. Despite so, the peace talk ended without any serious problems, and the leaders of the Three Factions successfully signed a peace treaty.
In Volume 5, he and the rest of the Satans attended the opening ceremony for the Young Devils Gathering, asking each of them to speak out their dreams for the future and starts the Rating Game for the Young Devils Gathering by arranging a Rating Game between his sister, Rias, and Sona Sitri, Serafall's sister, handing a medal to Saji after the match for his excellent performance.
In Volume 6, Sirzechs appears in Rias and Diodora Astaroth's Rating Game, which had been interfered by Khaos Brigade's Old Satan Faction where he confronted one of the leaders of the Old Satan Faction, Creuserey Asmodeus, attempting to reason with him to no effect before being forced to fight and kill him.
In Volume 8, Sirzechs appears in the Hyoudou residence during his supposed meeting with the other Satans, informing Rias that she will be undergoing a ceremony at the Ruins of Connection. Later on, he, Grayfia, and the other Satans acted as the Satan Rangers during the trials at the Ruins of Connection where he fought against Issei in the last trial and was able to overwhelm Issei with ease even after Issei used Rias' breasts as a power up.
In Volume 9, he and Azazel has a conversation on the Hero Faction, talking about how they are gathering Longinus and Balance Breaker users in their organization.
In Volume 10, he appears after Issei's battle with Sairaorg informing him about his promotion test to Middle-Class Devils.
In Volume 11, he revisits the Hyoudou Residence to get the confirmation of Issei, Akeno, and Yuuto for the middle-class promotion, telling Issei he can call Rias by her name even in front of him before once again telling him to call him brother, which caused him to be hit by Grayfia using a harisen, telling him that he is going overboard. He also arranges for Ravel to become Issei's manager.
In Volume 12, Sirzechs and Azazel went to the Realm of the Dead to confront Hades, the God of the Realm of the Dead, attempting to prevent Hades from making any moves on the Underworld. Sirzechs later reveals his "true form" to comply with Hades' demand but warns him that he is unhappy with what Hades did to his sister, Rias, and his brother-in-law, Issei, and assured him that should they fight, he would eliminate him without restraint or hesitation. Afterward, he and Azazel discussed about the aftermath of the crisis as well as about "one", known as the individual, and the "circle", known as the group.
Sirzechs was seen at the end of Volume 17, talking with the captured Euclid, asking why Euclid did such actions and comments that Issei is a brother that he can be proud of which Euclid sarcastically apologizes that he couldn't do the same while calling Sirzechs naive.
Sirzechs was seen talking to Azazel in the latter part of Volume 18 where they talked about the floating island Agreas that was stolen from them by Rizevim. Sirzechs told him that what was inside the island was essential for the creation of the Evil Pieces and the Brave Saint cards. He also told that there are only one thousand sets remaining and it is crucial for them to retrieve the island as the Evil Pieces has already made a deep impression on the culture of the Devils and the Underworld.
In Volume 21, Sirzechs appears to help Issei when fighting against the 666's core. After both of them fail to deal any sufficient damage on 666, Sirzechs assembles his peerage to implement Azazel's plan of trapping 666 inside the Isolation Barrier Field. Before leaving, Sirzechs hypnotizes his wife Grayfia, leaving her behind much to her dismay as Sirzechs proceeds to depart along with the remaining members of his peerage while Issei looks on in distraught.
Сили та здібності Редагувати
Immense Demonic Power: As the current Lucifer and leader of the Four Great Satans, Sirzechs is one of the most powerful Devils in the Underworld. In fact, along with Ajuka Beelzebub and Rizevim Livan Lucifer, he is one of three Devils considered Super Devils, with their powers and abilities transcending beyond the boundaries of the regular Devils, far exceeding even those of the Four Original Satans. His father, Zeoticus, has stated that Sirzechs and Ajuka's immense power made it so that there was no other position worthy for them besides being Satans. Ddraig upon seeing Sirzechs' True Form for the first time, felt awed at Sirzechs' strength calling him a true monster, a further testament to Sirzechs' strength.
- Сила Руйнування (滅びの力, Horobi no Chikara): Sirzechs inherited the Power of Destruction from his mother. He has overwhelming mastery of his Power of Destruction that allows him to eliminate anything it touches. Azazel had stated that the main reason why Sirzechs was chosen to be a Satan was due to his mastery of the Power of Destruction.
- Ruin the Extinct (滅殺の魔弾, Ruin za Ekusutinkuto): Through years of training along with the Demonic Power talents of the Gremory, Sirzechs is able to form his Power of Destruction by focusing its power into numerous highly mobile small spheres able to eliminate things without a trace as well as circumvent the defenses of his target, resulting in minimal damage to the surroundings. He was able to precisely control his destruction energy sphere to enter Creuserey's body through his mouth and destroy Ophis's snake without causing any damage to the latter. During his fight with Issei, Ddraig noted that Sirzechs' Power of Destruction is at an abnormal level, further noting that Sirzechs may have placed all his talent and effort into the concept of “eliminating”.
- Human-Shaped Aura of Destruction (人型に浮かび上がる滅びのオーラ, Hitogata ni Ukabiagaru Horobi no Ōra): Sirzechs' true form. He can convert himself into the Power of Destruction that destroys everything regardless of his will. The full releasing of his powers caused an earthquake in the complete Realm of Dead. According to Azazel, Sirzechs compresses the Power of Destruction into a human shape that releases demonic powers that are ten times more powerful than the original Lucifer. This form's power is enough that Azazel also commented that Sirzechs could have easily defeated Hades, one of the Top 10 Strongest Beings. Although, Sirzechs is unable to fully control it as the Power of Destruction spreads without his command.
Master Hand-to-Hand Combatant: Sirzechs is also highly skilled in hand-to-hand combat, combining physical combat skills with his Power of Destruction, Sirzechs easily overwhelm Issei, another master hand-to-hand combatant in his Scale Mail Armor, in a fist fight. Master Technician: Issei revealed that Sirzechs is a technique type fighter that polishes and masters all of his demonic powers and skills. When he fights Issei in Volume 8 he can control his power of destruction and use his magic skills in different ways, to overwhelm Issei. Master Magician: According to Akeno, Sirzechs is an ultimate Wizard-Technique type fighter, in addition to the Power of Destruction, Sirzechs has exceptional skills in using magic, able to use defensive magic powerful enough to easily defend against demonic power attacks from Creuserey, who's empowered by Ophis's snake to have Satan-Class powers, he can also use transformation magic as well as teleportation spells, he learnt from Azazel a hypnotism spell powerful enough to hypnotize Grayfia a Satan-Class Devil.
- Transformation: Sirzechs also appears to be proficient in using transformation magic, as Okita mentioned that he met Sirzechs in the form of a black cat.
- Teleportation: Sirzechs is also able to give access to people to use teleportation from the human realm to the Underworld immediately.
Flight: Being a Devil, Sirzechs can fly using his wings.
- Sirzechs claimed in Volume 6 that he once dreamed of being a musician, which was fulfilled when he composed the Oppai Dragon song to deactivate Issei's Juggernaut Drive.
- Sirzechs is the only person among the devils who was able to make a sacred creature into his servant.
- Sirzechs is over one hundred years old, having reincarnated Souji Okita as his Knight in the late 1800s.