Sekke is a teenager with a lean build and medium-length light-colored hair. His hair is combed backward and held together with a dark-colored hairband, leaving only several strands left hanging in front of his forehead.
Sekke's attire consists of a light-colored shirt with a dark-colored vest with a wide V-shaped collar on top of it. He also wears light-colored trousers and a pair of dark-colored high boots that have a pair of belts on each of them. In addition, Sekke wears a belt that is connected to a pouch that he uses to carry his grimoire. The pouch is placed on his left-hand side. On top of everything, Sekke wears a coat with long sleeves and horizontal stripes design.
As a member of a Magic Knight squad, Sekke is wearing the squad's signature robe. It is made out of simple fabric with a hood and only covers his torso. It is held together in the middle of his chest. The squad's insignia is positioned on his left side.
Sekke is a cunning man that would commit any act to increase his chance on gaining his desire. This side of him is reflected when he intentionally stay near Asta during the Magic Knights Entrance Exam so the captains could compare his abilities solely with the former's poor performances. In addition, he is also a very conceited person that likes to insult people whom he believes to be beneath him or he would create lies that elevate himself when he is with someone whom he believes to be above him.
Furthermore, Sekke is also a womanizer that loves to flirt with women whom he finds attractive. His flirtation moves usually consists of standing in a seductive manner and giving them speeches that showcase his romantic side.
At the age of 16 years old, Sekke enters the Magic Knights Entrance Exam for a chance to be accepted into a Magic Knights' squad. In order to increase his chance, Sekke swiftly approaches Asta whom he deemed to be the worst participant after seeing his performance for the first test. Sekke then stays near Asta throughout the exam in an attempt to make the captains that oversee the exam to judge his abilities with Asta as the only comparison.
At the end of the exam, when William Vangeance reveals the final combat test, Sekke quickly asks Asta to be his partner in which the latter accepts the offer. Before the match start, Sekke finally showed his true intention to Asta. While the latter turns speechless, Sekke activates a defensive spell and offers Asta the first attack as the match starts. Unbeknownst to him, Asta charges at Sekke at an alarming speed and renders him unconscious in the process. Despite his defeat, Sekke is recruited into the Green Mantis squad.
After the exam is finished, Sekke manages to get accepted into a squad but left with bitter feeling towards Asta. He then follows the latter to the bathroom and plans to launch a sneak attack at him. Unfortunately, his plan fails as Yuno steps in and breaks his curse spell. Sekke tries to give Yuno an excuse but he decides to leave after sensing the latter's intimidating aura.
A few days later, Sekke goes to Kikka's black market and gambles with an elderly woman. While he is suffering quite a loss against the old lady, Sekke begins to complains to himself about his experience working with his new squadmates. Subsequently, he notices a couple of beautiful ladies, Vanessa Enoteca and Noelle Silva, shopping not far from him. He immediately approaches and flirts with them but only to receive a cold and harsh rejection from them.
At that moment, Asta interrupts their conversation in which completely surprised Sekke as he learns that those ladies are acquainted with the former. While they are having a conversation, the elderly woman who was gambling against Sekke is being robbed by a thief. As Asta begins his pursuit, Sekke also activates his magic to stop him as well. Sekke manages to ram the thief with his spell after Asta nullifies the thief's magic, but Sekke is stabbed by the thief.
As the thought of death fills his mind, Sekke tries to convey his final wish to Asta, who rejects his wish while encouraging Sekke to live. When Vanessa reveals that Sekke's injury is harmless, he immediately leaves, trying to cover his embarrassment.
About a week later, Sekke shaves his facial hair and attends a blind date with a couple of acquaintances. During the date, he constantly boasts about himself with several lies about his involvement in the Royal Capital's invasion. It causes the ladies to significantly lose interest on him, as they remain silent throughout the date. When he asks Noelle, who is waitressing, for a drink, she blasts him with her Water Magic. Later on, a big burly man suddenly falls on top of Sekke. Since he is stuck under the said man, the ladies decide to bail from the blind date.
Sekke takes his two friends to Raque and they laugh at Finral Roulacase's attempts to talk to women. Sekke then tells his friends to go find girls of their own, directing them toward Noelle and Vanessa. After Noelle rejects them, Sekke recognizes the girls and is then sent flying as the other Black Bulls stampede across the beach.
A week later, Sekke cowers behind a rock after witnessing Vetto defeat fifty Magic Knights.
During the Star Awards Festival, when Yuno and Asta are recognized as the most successful rookies, Sekke denounces them as commoners and Asta as a fraud without magic power, so the crowd starts doubting the pair, but Sekke is then flabbergasted by Yuno and Asta's display of power. Later when Asta criticizes Augustus Kira Clover XIII, Sekke calls the boy a dumbass.
As their first match begins, Sekke freaks out because he is weak, and Fragil notices Sekke panicking and asks if he is okay and if he is strong like the Black Bulls. Sekke starts to act cool and suggests that he blast around on his Shooting Star, with which Langris agrees. As Team G has finished putting up a barrier around their crystal, Sekke and Langris come riding towards them and Langris easily destroys the crystal and its defense, winning the match for Team G.
- Curse Magic: A magic that allows Sekke to imbue curse into an object that he created out of bronze.
- Grimoire: Sekke possesses a grimoire that contains his bronze-based magic spells. The grimoire has light-colored covers with a large T insignia on both covers with a dark-colored horizontal lines at the middle. It also has a three-leaf clover insignia on the front cover.
- Sekke's favorite things are being in a cool ambiance and petty gamble.