Brain Unglaus has brown eyes with blue hair and the appearance of a wild beast. He is equipped with chainmail and wears a necklace and ring, which are infused with protection magic. His whole body is lean and his muscles are tough as steel and tempered through experience.
When first introduced, Brain acted very arrogantly, thinking that he was the most powerful, having surpassed Gazef after completing his training and that he was ready to defeat him in a rematch. In his pursuit of becoming the strongest, Brain decided to abandon all, except his dedication for the sword, and that anything was right as long as it would help him to defeat his rival.
His personality changes drastically after having a run-in with Shalltear. Having his confidence completely crushed and getting a feel of what true terror is like, his attitude changes to one where he is completely depressed, hinting at a suicidal tendency. Furthermore, he abandoned his underlings in Death Spreading Brigade and escaped by himself showing that he was reduced to a coward, or that he never cares for them.
He eventually does a complete overhaul after meeting Climb and Sebas Tian. He changes to a much friendlier person who starts to think that strength is more than simply being skilled with a sword. He also becomes grateful to Gazef and the two develop a deep friendship.
Originally a farmer, Brain was gifted with what could only be described as a god-given talent in the mastery of the sword. He has always believed himself to be the strongest fighter inside the Kingdom, having never lost a fight before he entered the grand tournament to decide the King's guard captain. He easily fought his way to the final where he faced off against Gazef Stronoff. A grand and close battle ensued between the two, but eventually, he would taste his first defeat at the hand of Gazef.
His win-streak was shattered and his confidence as an unbeatable warrior took a hit. He then decided to do everything he could to become stronger, so he would truly become unbeatable. While he received many offers from nobles, he declined them and went on a journey to improve himself, meeting various people such as Rigrit Bers Caurau. At the same time, in order to make a living, he started working as a mercenary for the Death Spreading Brigade.
The Bloody Valkyrie Arc
- Main article: The Bloody Valkyrie Arc
When the hideout of the Death Spreading Brigade was being attacked, Brain confronted Shalltear Bloodfallen and tries to defeat her, but suffered a devastating defeat, failing to even scratch her. His absolute confidence was shattered by the immense difference of power between him and the vampire. He fled crying, escaping the massacre through a hidden tunnel.
The Men in the Kingdom Arc
Brain retreated to the capital city of the Re-Estize Kingdom in order to hide from Shalltear. Gazef finds Brain slumped on the side of a street and brings him back to his place. Brain is still shaken by his momentous defeat and uses his time to recuperate. Whilst walking through the streets, Brain overhears a commotion and discovers Sebas Tian, as he incapacitates the men who were attacking a young boy. He follows Sebas and Climb, into an alleyway where he sees Sebas release an extreme amount of killing intent, directed at himself and Climb. This was Climb's requested training under Sebas. After the bloodlust ends, Brain reveals himself and converses with Sebas and Climb before fighting off a group of assassins that were also following Sebas.
After defeating the assassins, Brain, Climb, and Sebas travel to the brothel where Tuare was discovered. They attack the brothel and capture Succulent, one of the members of Six Arms, and a member of Eight Fingers, Cocco Doll, leader of the slave trade department. Following the battle, Brain goes back to rest at Gazef's house and they discuss the events and his defeat at the hands of Shalltear.
Later, Brain is sent to partake in another raid on the Eight Finger's hideouts alongside with Climb. He briefly talks with Gagaran of the Blue Roses before beginning the operation. When they begin, they have a scout infiltrate the compound they are to attack, who discovers that all of the remaining six arms are within the compound, along with a captured girl. As they're about to fall back, they meet Sebas, who came to rescue the girl, Tuare.
Brain, Lockmeier, and Climb all infiltrate the back of the compound in order to rescue Tuare while Sebas deals with Six Arms. The trio use invisibility to infiltrate the compound and break Tuare out of her cell. As they are escaping, they are ambushed by Zero, the leader of Six Arms, and are forced to fight. At the same time, they discover that the Tuare, they rescued from the cell was actually Succulent in disguise. In the encounter, Lockmeier and Climb are forced to fight Succulent while Brain fights with Zero. Climb and Lockmeier defeats Succulent and as the battle between Zero and Brain nears an end, Sebas appears and defeats Zero with ease. Brain, Climb, and Lockmyer all exit the building, only to witness a wall of fire off in the distance, which is thought to be another one of the hideouts being currently raided.
During the battle, he, Climb, and Lockmeier are inside the wall of fire and they find that people are missing from their homes. During their search, he spots Shalltear and recognizes her despite the disguise she's wearing. Knowing that all would be dead if the vampire finds them, he decided to act as a decoy, so he leaves Climb and Lockmeier. He fights Shalltear and uses "Nail Clipper" - a technique combined of Four Fold Slash of Light, Field, and God Flash - to cut her fingernail. This pleases him greatly and he leaves jubilant. Shalltear pursues him but stops after seeing the two other people Brain is heading for.
The Magic Caster of Destroy Arc
- Main article: The Magic Caster of Destroy Arc
Brain is present during the massacre at Katze Plains along with Climb and Gazef. When Gazef challenges Ainz to a one-on-one duel Brain protests it but Gazef convinces him to back down and be a witness to it. He watches Gazef die after getting struck by an instant death spell. Ainz allows him and Climb to take the body, which Brain carries on his back.
The Ruler of Conspiracy Arc
- Main article: The Ruler of Conspiracy Arc
It was mentioned by Princess Renner that Brain Unglaus is searching for a new replacement for Gazef Stronoff in the Royal Capital and plans to train the replacement to become the next Warrior Captain.
Abilities and Powers
Brain is a Genius/Fighter class compared to most other melee-oriented combatants who have the Fighter class as their starting class. While most learn martial arts that have been passed down through the ages, Brain has been developing his own unique martial arts.
In the Web Novel, when he lost his humanity to Shalltear and gets turned into a Vampire, Brain would later step into the Realm of Heroes in terms of total levels thereafter. According to Maruyama, Gazef Stronoff cannot win against someone of that level anymore. However, it does not mean that there are no prospects for victory for Gazef.
- Fighter (Genius)
- Sword Master
- Sword Saint
- Ability Boost: Raises the overall strength of the body.
- Capacity Building: Increases the bodies overall capacity.
- Cutting Edge: Able to gather air to give an extra cutting edge to a blade.
- Field: A unique martial arts that Brain himself has made, allow Brain to perceive everything within a three meters range. In simpler words, it raises the user's accuracy and evasion to the utmost limit.
- Fortress: Can be used to offset the enemies attacks.
- Fourfold Slash of Light: It is a skill Gazef used to defeat Brain in the tournament. Brain learned this skill through his own effort.
- Front Cut: It allows the user to cut directly one's opponent using the front of the weapon they are using.
- God Flash: Third unique art that came from practicing Instantaneous Flash millions of times, this attack is so fast that even when cutting through someone, blood will not stick to the blade.
- Heavy Blow: Raises the weapon's crushing capability.
- Instantaneous Flash: The second unique art, allows Brain to attack at an extreme speed.
- Nail Clipper: It is the result of the unison with three other martial skills: Fourfold Slash of Light, Field, and God Flash to create this skill against Shalltear Bloodfallen.
- Oblique Strike
- Severing Blade: It would allow one to take down strong opponents in a single attack.
- Strong Assault: Increases attack power allowing oneself to damage someone with heavy armor.
- Vertical Strike: Allows the user to execute a strike attack from a vertical axis
- Wind of the Great Forest: Brain's trump card. A combination of Field and God Flash. It was named after the sound of blood spurting shortly after severing the neck.
- Katana: Its a normal unenchanted weapon bought from a city in the middle of the desert located south of Re-Estize Kingdom. It's cutting capability surpasses those of ordinary magic weapons.
- Necklace of Eye: It protects his eyes when activated. Grants resistance to blind status, night vision, light filtering.
- Ring of Magicbound: allows its wearer to bind a low-level spell to the item and invoke it with the ring as the catalyst.
- Chain Shirt: It is a chain armor shirt that is relatively light and protects the torso. Brain wears this under his normal shirt.
- Potion of Lesser Strength
- Potion of Lesser Dexterity
- Potion of Magic Weapon
Brain used to see Gazef as his nemesis and rival due to his defeat at the hands of the Kingdom's Strongest Warrior, wishing to overcome him to prove that he was the strongest. By the time that he met Shalltear, Brain thought that he was ready to confront Gazef and believed that when the two meet each other they would have a duel to the death.
However, that all changed right after having his self-confidence and willpower crushed by Shalltear Bloodfallen. Unlike how they've met each other during their match together at the tournament, Brain confronted Gazef yet again, but this time he was a shadow of his past self. Brain had almost prompted himself to even think of wanting to commit suicide before Gazef stepped in to stop him from thinking that way. Brain comes to later respect Gazef for his action and appreciates his kindness for helping him out in his time of need.
He is greatly saddened by Gazef's death and states that he thought of him almost as a father figure.
Originally, Brain has once used to look down on Shalltear and thought of her as nothing more than a foolish and arrogant demon that overestimated her abilities. After Shalltear renders Brain's most powerful techniques completely useless with only her pinky finger alone, this causes Brain's spirit as a warrior to become broken, realizing that she is an entity who cannot be defeated by him because he is just a human. Brain would then go on and flee from her with everything he has. During his escape to the Re-Estize Kingdom, Brain is unable to sleep soundly due to having nightmares about her following him until now.
After meeting Sebas and Climb, Brain has somehow managed to have gained back his lost confidence. Later on, Brain would come across Shalltear once again and already knows that he is no match against her. However, he was still determined on deciding to confront her again. Using his strongest abilities, Brain was able to at least manage to cut off a tip of the nail from Shalltear's pinky finger. This is tremendously joyful to Brain's pride that his entire life of training wasn't all for nothing.
After seeing Climb survive being exposed to Sebas' killing intent despite being much weaker than him and finding out the reason he could stand up to a being whose strength is on par with Shalltear is because he wants to protect the Princess, Brain went through a drastic change in his personality, restored his confidence, and began to care for Climb, helping him on many occasions.
Brain greatly admired Sebas' strength and believed him to be as strong as Shalltear. Brain also believed that even if he and Gazef were to fight Sebas together, they would still be outmatched.
- In the Web Novel, he becomes a vampire under Shalltear Bloodfallen.
- Brain managed to chip off Shalltear's pinky fingernail using Fourfold Slash of Light, the second time they met.
- Brain is the only person so far to know about the vampire's true identity known as Shalltear but still believes that Honyopenyoko is another vampire that Momon had slain instead.
- His hair is blue because he dyed it.
- Maruyama intended to make him homosexual, but then decided against it and simply made him obsess with sword skills.
- After the final of the Royal Tournament, his fight with Gazef became legend and song and many powerful entities (Six Arms, workers, Windflower Scripture) started to take the names of Brain & Gazef in high regard.
- (Facing Shalltear): "These foolish monsters that think they're the strongest, they're all the same. They think that humans are weak, that our bodies are fragile, our abilities nonexistent. But I will teach you how dangerous it is to underestimate us."
- (To Gazef): "Stronoff! We can never reach the world of the truly powerful, no matter how hard we try. As long as we’re born human, this is the truth. In the end, we're just children holding sticks. We're playing with swords now, but we are still mere children pretending to be swordsmen."
- (To Gazef): "Stronoff. Strength achieved from the sword really is garbage. It's useless in front of true power."
- (To Succulent): "The strength that you speak of is the same. We're probably speaking about similar things so let me give you a warning. Even if we claim that we’re strong, we’re nothing special."
- (To Gazef): "Well, I guess I won't be able to protect the Princess and it'll be a shame to not be able to train Climb any more...but Gazef, I owe you. I'll do any dirty deed you want with a smile on my face."
- (To both Gazef and Ainz): "Wait, wait a minute! Hang on, Gazef! I can always die alongside you! Don't go alone! My lord Sorcerer-King! Please, I beg you! I know this is shameless beyond belief, but this is a heartfelt request! Please allow us both to face you! I know it won't inconvenience you in the slightest!"
- (To himself after Gazef's death): "Why did you choose to die? Wouldn't it have been fine to run from that monster? Wouldn’t it have been like conserving your strength? Why?! If you had to die, I wanted to go with you!"
- (To himself about Gazef): "You...like this...I admired you...I wanted to die with you. Why wouldn't you let me fight by your side? Why didn't you tell me that I could die with you!"