Kamen Rider Build (The Big Crunch)

Sento Kiryu, better known by his alias of Kamen Rider Build (or just Build), is an alternate-world version of Prime World of Build's own Sento Kiryu. He is the protagonist of the short series Kamen Rider Build: The Big Crunch. Still a Genius physicist, Sento utilizes his own world's Fullbottles and Pandora Box in conjunction with new-world Fullbottles to defeat the ever-present Smash Organisms and Evil Riders of the World he had hoped would've been free of both.

History
This alternative Build has a history completely mirroring the original Prime version; succeeding in fusing two Universes and erasing both to form one "better" version. However unlike what he had wished, he found himself in a world where they Sky Wall is even larger; literally splitting the Earth into quarters. Smashes, once only created intentionally, now runs rampant as Nebula Gas spews across the walls and Animals are subjected to them.

With such widespread access to Nebula Gas, Riders also became prevalent and more importantly, the New Faust possesses the most Riders out of any around the Globe.

Finding himself alone and without allies, he has to use his intelligence and inventions to fight Faust and hopefully initiate another Universe Merge; one truly without Riders or Monsters.

Abilities

 * High Hazard Level Physiology: Although starting out at a mere Hazard Level of 1.2, his previous experience of having a high Hazard Level allows his body to quickly raise its Hazard Level after repeated exposure to Nebula Gas; quickly reaching and averaging Hazard Level 3.3 after only a single visit to a Sky Wall. This allows Sento to eventually, near the end of his journey, reach a Hazard Level of 10.0 before it jumps off the scale.
 * Nebula Gas Measurement: As a person who's extremely tuned to Nebula Gas, Sento is able to accurately gauge the Hazard Level of enemies even when outside of his Build forms. His range of accuracy is within 1 or 2 decimals.
 * Genius Intellect: Sento, like his Prime Counterpart, is a Genius is many scientific fields and is not only able to invent and create ground breaking theories but also implement and perfect them. He displays this on many fronts; his Rider System being superior to all others in the New, combined world and practically instantly learning 2 new Languages in order to better communicate.
 * Fullbottle Augmentation: Sento retains the ability to enhance himself with the aspects of a Fullbottle with the effects becoming stronger the higher his Hazard Level is.
 * Rabbit: Grants Sento superhuman speeds. With a Hazard Level of 1.2, he's able to move so fast that normal humans can no longer see him and outpace Smashes. With a Hazard Level of 3.3, this increases to the point that Bullets practically stop moving from his view.
 * Tank: Grants Sento Superhuman Durability. At first this allows Sento the ability to take hits better in general; surviving falls that would normally kill the average person. With a Hazard Level of 3.3, this increased to allowing Sento to become Bullet Proof and even take rockets and only suffer minor scratches.
 * Dragon: Gives Sento Superhuman Strength and Pyrokinetic capabilities. Because of his bond with Banjou, this bottle is particularly powerful and even with a Hazard Level of 1.2, can weld vehicles together in seconds.

Weaknesses

 * Nebula Gas Overexposure: Due to his unnaturally high affinity for increasing Hazard Levels, Sento's body has the unique danger of becoming overexposed and becoming a sort of "Super Smash" with immensely dangerous potential.
 * Hazard Trigger: Much like before, the Hazard Trigger can potentially overstimulate Sento's nervous system and cause him to work purely off of instinct (Which usually involves destroying whatever is infront of him).
 * Over-limit Hazard Level: At Hazard Level 10+, Sento faces the entirely new and unforeseen problem of his Hazard Level being too high for normal Fullbottles to handle; shattering and breaking them. Large Fullbottles like RabbitTank Sparkling or Genius seems to be exempt from this limitation.