He is voiced by Hideyuki Tanaka.
As Professor Alba, he acts like a scatterbrained but friendly professor who is willing to risk his life to research Zemurian ruins. He acts favorably to Estelle and Joshua in order to manipulate them into advancing the Gospel Plan. When his true identity is revealed to Joshua, he no longer acts humorous, but still has an air of politeness.
Despite his outwardly affable demeanor, Weissmann enjoys the suffering of others, as shown when he watches Joshua agonize over his grim past. He fully admits to being a sadist, to the point where he considers being called one a compliment rather than an insult.
Weissmann's goal to use Stigmas to "correct" humanity show that he's very self-righteous, to the point where he blames the victims of his plans for being sinful. He sees himself so far above humanity in intelligence and morality that he believes any suffering they experience at his hands is justified. Weissmann's pride ultimately keeps him from realizing that he's part of the problem that he's supposedly trying to fix.
Weissmann was originally an ordinary citizen from North Ambria until the country was destroyed by the Salt Pillar incident, leaving him orphaned. He was taken in by the Septian Church, where he rose in its ranks and became a bishop. Unfortunately, his desire for knowledge and power caused him to perform experiments to create artificial Stigma, causing him to be excommunicated. He is then recruited into Ouroboros by the Grandmaster.
Professor Weissmann is an evil wizard. He works under the mysterious crime organization, which is known as Ouroboros as the agent with the position the 3rd Angis - faceless. He is the one who is responsible for the Hundred Days War, which results in the death of Agate's younger sister, Michelle and the Tragedy of Hamel Village. This causes Joshua's heart broken and changes Leonhardt's point of view about the humanity. He appears and introduces himself as Weissmann and he promises he will cure Joshua's broken heart, under the condition both Joshua and Leonhardt work with Ouroboros afterwards. He remoulds Joshua into a ruthless assasin, who assasinates a lot of people during his missions, thus granting Joshua the alias "The Black Fang". This is to ensure Joshua won't show any fear during his mission and thus failing his missions and his personal "experiment" will go well successfully.
Later, Joshua is sent to assasinate a target in a mission, who is Cassius Bright, who is the father of Estelle. When Joshua fails his mission, he sends some of his henchmen to kill Joshua, only being interrupted by Cassius Bright timely who saves Joshua's life and takes him back to his house and adopts him. Joshua first meets Estelle Bright in the Brights' house, and lives with them happily afterwards. Unfortunately, this was also within Weissmann's calculations, who used Joshua as an unwitting agent to gain information on the Bracer guild.
The Legend of Heroes - Sora No Kiseki FC
In the Rolent Region, Estelle and Joshua encounter Weissmann in his Professor Alba guise at the top of Esmelas Tower. Alba claims to be an archaeologist who wants to research the Tetracyclic towers, which is technically true while hiding his true motives. Joshua feels nauseous upon meeting him, but nothing comes of this feeling for now.
Estelle's party meets him again in Amberl Tower, which they suspect as a potential hiding place for the Capua Bandits. Instead, they find Alba in danger of being attacked by monsters and they admonish him for taking such risks for his research, not knowing that he's perfectly capable of defending himself.
In Zeiss, Alba reports to the Bracer guild that a group of Black-Clad soldiers went to Carnelia Tower. After that incident, he gets Estelle and Joshua through the gate to Grancel by claiming them as escorts.
In Grancel, Alba is shown in the audience of the martial arts tournament, suspiciously at the same time Kurt Nardin is struggling with amnesia.
After Colonel Richard is arrested, Joshua realizes that Alba's appearances during several of the coup's events weren't mere coincidences. Instead, Alba is really the Ouroboros Anguis, Weissmann, who used his mind control magic to manipulate Richard and other characters into partially unsealing the Aureole for him. Weissmann then restores Joshua's memory so that the latter can no longer travel with Estelle with a clear conscience.
The Legend of Heroes - Sora no Kiseki SC
Weissmann orders the Enforcers under his command to test out the new Gospel units, causing incidents in every region of Liberl. He is personally involved in one of them, where he and Loewe defeat the dragon Ragnard and use a Gospel to control him.
He and the Enforcers allow Kurt Nardin's Bracer team to find one of their bases, allowing them to defeat the Bracers and brainwash three of them. Kurt is sent back via boat to Kingfisher Inn in order to lure Estelle to investigate their base. Estelle is then kidnapped and sent to the Glorious airship, where Weissmann tries to tempt her into joining Ouroboros to become strong and find Joshua. This is actually a ruse to use Estelle as a hostage against Joshua, keeping the former assassin from making a serious attempt to destroy their airship.
Weissmann orders the Enforcers to use their Gospels at the Tetracyclic towers, which fully undoes the seal on Aureole. This causes a country-wide Orbal Shutdown Phenomenon that completely cripples Liberl's infrastructure, as well as the orbal devices of Erebonia's border towns. Worse yet, Weissmann invites further chaos by sending leagues of Jaegers and robots to terrorize the country in order to keep the Bracers and military busy. When the Bracers start gaining some ground in this situation with their ZFG devices, the Enforcers and their Jaegers invade Grancel and take Queen Alicia and Princess Klaudia hostage on Weissmann's orders. This turns out to be yet another distraction when Osbourne sends in steam tanks based on advice from Weissmann and Ouroboros.
Estelle's group makes it to the Liber Ark, where Weissmann and the Enforcers await. After Loewe's defeat and redemption, Weissmann attacks the former and activates the stigma on Joshua to control him. The party confronts him again, where he tries to convince them that humanity needs to be brainwashed with the stigma to prevent them from slipping into endless war or complacent hedonism. Estelle shoots down his arguments by pointing out that the people of Liberl are doing just fine in working together to survive the disaster he put them through. He then orders Joshua to kill Estelle, but Kevin's remedy causes that order to backfire and remove the stigma, freeing Joshua from Weissmann's control for good. The team manages to defeat Weissmann, only for him to fuse with the Aureole and become invincible due to a barrier. Loewe shows up and gets Weissmann to confess to starting the Hamel incident, earning the entire party's disgust. The former Enfocer then sacrifices himself to destroy Weissmann's barrier so the party can defeat him.
Weissmann returns to his human form and teleports to a different part of the Liber Ark, but is confronted by Kevin. His attempts to use Evil Eye on the priest fail and he is shot with a bolt made from the Salt Pillar, causing him to crumble to death. As Weissmann dies, he curses Kevin for being a dog of the church. Campanella shatters his body and takes his staff, which still has the Aureole in it.
The Legend of Heroes - Sora no Kiseki the 3rd
Weissmann is still dead during this game, though only Kevin and Joshua are aware of this fact. After the Lord of Phantasma sends Kevin to Gehenna, a copy of Weissmann is waiting in front of the exit. Despite holding a grudge against Kevin for killing him, he's still obsessed with his Gospel Project and offers to brainwash Kevin into never feeling guilt or grief again. Kevin is momentarily tempted, but refuses this offer, causing Weissmann's copy to call him a dog again. The professor then summons Astarte and Rostrum to attack Kevin in order to force the priest into accepting the offer, but is defeated when Kevin unlocks additional power from his Stigma.
- He is similar to Colonel Muska's from Studio Ghibli's Castle in the Sky.