Kamen Rider Build for Faust x Yūri KR-AU
Kiryū Sento (桐生 戦兎) (who i picked for Faust), his rider motif is Rabbit, Tank, Science
Banjo Ryuga (万丈 龍我) (ofc, picked Ryuga for Yūri) his rider motif is Dragon
Faust was an illicit military research program focused on illegal experiments with Nebula Gas.
The organization is eager to use the extraterrestrial technology of the Pandora Box to produce more weapons such as the Smash monsters. According to Gentoku, one of Faust's objectives is to create the "Ultimate Lifeform," hence their experiments with the Smash organisms, which turned out to be finding suitable candidates (whose Hazard Level is higher than 2) for the weaponized Rider System.
In Build NEW WORLD: Kamen Rider Cross-Z, revealed that the true purpose of Faust's founding was to raise Banjo Ryuga's Hazard Level so he would become strong enough for Evolto himself to absorb and regain his true powers.
The organization's name is derived from a German tale about the title character Faust, an intellectual scholar who sells his soul to Satan to obtain unlimited knowledge and pleasures such as wealth.
The former fits the description of the organization, as it is science-based and trades away its humanity to gain power in the form of creating weapons.
(which also what our lcb Faust based from)
Originally a man with no memories of his past, one of the greatest traits Sento has kept from the transition from Takumi is his genius-level intellect, which he has displayed numerous times with his advanced knowledge of science, mathematics, engineering, and cryptography. Sento is easily attracted to anything he deems mysterious or interesting, such as a new innovation or a lead towards uncovering his past, and will relentlessly pursue it.
This will continue until either he reaches a conclusion or someone forcibly stops him during progress.
Another trait that is carried over from his father is his polymathism, which is accompanied by an inflated ego and sharp tongue: he likes to praise himself for his works, and often mocks Banjo for his comparatively lower intelligence.
Sento often relies on his own skills to solve problems and never expects sudden assistance from others, so when it happens, he tends to either be surprised or turns them down. Also, Sento can be easily caught off guard when he accomplishes anything or witnesses something unexpected and new which excites him, because of his reliance on his intellect. In this state, he is vulnerable to any surprise attacks.
As firm pacifist, he believes that science should be used for the sake of humanity, and harshly opposes using it for war. His selflessness and sense of duty causes him to try and shoulder the burden alone rather than involve others, whether he can carry that burden or not.
Genius-Level Intellect: Sento's most defining trait is his intelligence. He is a genius in several fields of science and has an advanced knowledge of particularly both physics and chemistry.
Master Scientist: A exceptional scientific prodigy, Sento is a ingeniously resourceful, knowledgeable, and brilliant scientist who is well-educated in many different fields of science, including physics, chemistry, and advanced mathematics.
Master Engineer: Sento is an extremely talented and prolific engineer and technician, having been able to make many complicated inventions. He is also a master craftsman. Hence, he created fake versions of his gear to use as bait, which were completely indistinguishable from the genuine article with the naked eye.
Time Travel Knowledge: Sento also seems to understand the fundamentals of time travel as well
(Ryuga Banjo is the son of Yuri Banjo and her unnamed husband making me laughed for no reason-)
Banjo is an extremely hot-blooded and impulsive man who tends to lash out quickly. He is shown to be easily provoked and startled in most situations, which is often joked on by Sento.
While nowhere near as intelligent as Sento, Banjo prefers to confront problems directly using his fists and doesn't want to involve other people in his own problems.
Also, unlike Sento, he does not overthink things, preferring to use common sense, as shown when he was easily able to guess two Best Matches on his own. His impulsiveness increased following his initial usage of the Sclash Driver, which imprinted him with the single task of getting stronger and beating down his opponent.
These side effects also remove his rationality to make decisions, but he is able to overcome these weaknesses with his strong will to save Sento from rampaging with the Hazard Trigger.
Beneath his tough exterior is an honest, selfless and honorable individual who cheated during a match to gain the money needed for his fiancée's medical treatments, causing him to receive a lifelong ban from the ring.
He is extremely protective to those who he trusts, as he attacked Blood Stalk out of anger for the sake of both Sento and Misora, completely disregarding the fact that Stalk framed him.
Banjo appears to hold a lot of fondness for his childhood, as whenever he describes the circumstances of his birth, a bright smile is always on his face.