Jet is described as a teenager with dark hair, a sickly skin tone, bags under his eyes while paradoxically still being handsome. He also wears an eyepatch on his left eye  for reasons related to his Talent and not medical reasons.
Jet Testania is a character that appears in Part 2 of the web novel of Overlord and is the main protagonist of the school/Gakuien arc. He features prominently as the point of view and is the impetus for much of the arcs events as someone Ainz has his eye on.
Jet was born into a disadvantaged family. His mother once worked for the Furt family. Jet discovered his magical aptitude thanks to Arche who also warned him of the dangers of openly walking around with his Talent not being covered up. He considers Arche not only a benefactor but someone he still looks up to for being smart and talented despite having left the academy years ago. By the time he enters the Empire's Magical Academy, he no longer has a father in his life and his mother is dying from a mysterious illness simple Divine magic cannot cure. Despite all this, Jet somehow managed to befriend a lower ranked noble girl named Nemeru. Even though his mother frequently suggests Jet should pursue a proper relationship with her, Jet refuses and views her as a close friend only.
When the arc starts, we see from Jet's perspective waiting for Nemeru after school like he always does. However she runs late, and is followed by young nobleman from a very strong family and who also possessed superior magical ability being able to use Tier 2 magic, while Jet can only use Tier 1 and only a few at that, mainly using only spice making magic at his part time job that he refuses to accept a promotion at when they are even willing to pay the fees to allow Jet to leave the Academy without taking an administrative position like the Academy was designed for. This nobleman, named Rangobart Eck Waria Roberbad appears to frequently solicit interactions from Nemeru using the noble hierarchy to ensure she cannot refuse. Jet admits he would not mind if Rangobart loved Nemeru, but Jet knows that Rangobart only wants to use Nemeru. Using his powerless position in society, Jet prevents Rangobart from getting her to do as he wants by hiding her behind his back in a non-romantic gesture of protection. In particular, by being unrelated to nobles, Jet does not need to fear his reputation being ruined. However, he fears repercussions as time passes when he tries to find a job. So he aspires to become a knight to receive protection from noble backlash from Rangobart and others by using the Bloody Emperor Jircniv's reputation as a shield.
Unlike most students, nobles get to attend the Magical Academy easily by paying money to take easier tests while students like Jet have to work extra hard and study to receive a free education. Rangobart was one of those rare nobles that had wealth and talent making him imposing. In contrast, most nobles attended the Magical Academy not to learn but form connections. So someone like Rangobart who had pedigree, status, wealth, and talent would be able to reach heights Jet could not. Hence he needed a way to ensure his and Nemeru's safety from higher ranked nobles' influence.
Rangobart gets frustrated at Jet's petty interference of making up lies and preventing Nemeru from talking to him. He reveals his sneering facade and insults Jet's mother, implying she engaged in questionable activities. Before things can escalate, the student council president, Frieanne Waria Ran Guismondo comes and interferes. As she is someone approaching the third tier, she frequently can act as a shield for Jet at least until she graduates next year. But by the same token, once Rangobart reaches the second tier, he can exert similar influence. Nonetheless, Jet decides to use her and claim Rangobart was bullying. Jet then quickly allows her to deal with Rangobart and leaves with Nemeru as she winks in acknowledgement to Jet's ploy.
Due to being so poor and disadvantaged Jet cannot afford his own textbooks,so he has to review at the library. But unfortunately he has to work using his spice making magic. However, even if he accepted a promotion offer, it would not be enough to protect him from the ire of the nobles. Jet laments how he understood how his senpai dropped out of the Magical Academy to become an adventurer despite being able to use Tier 3 magic. Due to being overworked and stressed though his health is not faring well. Since he is a powerless as a commoner, he is in danger without a powerful shield to protect him from nobles like Rangobart. No matter, Jet places all his hopes on the knight order to protect him in the future but fears he may not be able to make it there.
Nemeru seeing this offers to lend him money. Jet accepts but he is conscientious about leeching off of Nemeru. He offers praises though when he hears her sister got hired by a powerful noble, enabling Jet to receive money without worries.
Once Jet reaches home, he finds his sickly dying mother bedridden again. She frequently coughs and Jet feels she approaches death with each cough. Jet had been struggling to buy a magical item to help her. Ever since his father died when he was young it had always been the two of them. The temples told him that only very expensive Divine magic could cure her, but only workers would be able to afford it. Even if Jet approached Adventurers they would not be able to heal her due to temple regulations. In fact, if an Adventurer did not charge, they would possibly disappear and die mysteriously. Even joining an Adventurer party and getting a team member to cure her with Cure Disease won't work because a higher tier magic is needed.
Mysteriously a stranger named General Ray visits Jet's home. Thankfully, he appeared to be dressed as a high ranking knight. They decide to speak in Ray's carriage, but it had a noble's crest Jet did not know despite having studied them. Inside Jet meets Sebas who offers to take him to have drinks but Jet refuses. Getting to brass tax, Sebas tells Jet his lord has recently acquired land and is seeking to require staff to help run it. He goes on to say Jet's name came up in this search. Feeling he was not qualified, Jet asks about the pay but it was three times the norm. Jet feeling either the noble had bad judgement or was placing too much value on his Talent holding eye or Tier 1 magic decides to refuse. When Jet cites the academy, Sebas offers to allow him graduate with the best grades possible and skip to graduation.
When Sebas offers the position at a later time, Jet lets slip that may be a problem on accident. The next day at his school Fluder joins his class as student despite being able to use tiers far above his teachers and mentioned throughout their history books.
- ↑ WN Part 2: Daily Life 4