Killbus

Killbus (voiced by Anri Katsu) is the former ruler of the Blood Tribe and the main antagonist of Kamen Rider Build NEW WORLD: Kamen Rider Cross-Z. After destroying his own planet, he spent years looking for his younger brother Evolto until he reaches Earth. Upon arriving, he takes the form of Sento Kiryu and steals his Build Driver, before opting for the appearance of Satoshi Kakizaki, he later transforms into Kamen Rider Killbus (仮面ライダーキルバス Kamen Raidā Kirubasu).

Sometime before the start of the series, Killbus was responsible for the destruction of the Blood Tribe home planet, Planet Blood, as well as the one giving them orders to destroy other planets. Before the destruction of said planet, Evolto escaped with Pandora's Box in hopes of making sure Killbus doesn't find it, prompting the latter to search for Evolto.

After the World of Build was merged into the World of Kamen Rider, Killbus arrived via the White Pandora Panel and copies the appearance of Sento Kiryu and later Satoshi Kakizaki. Taking the Build Driver from Sento, Killbus obtains the means to transform into his Kamen Rider form, Kamen Rider Killbus, which is even stronger than Kamen Rider Evol. Killbus plans to restore the energy of the Pandora Box and use it to destroy the entire universe.

Later on, he fought Ryuga Banjou, and his brother, over the Pandora's Box. Due to the Box reappearing into the New World, everyone from the original World of Build got their erased memories back, excluding Sento and Ryuga as they had kept their memories during the transfer. Despite having the upper hand initially due to his rider form being stronger than Evolto, Ryuga assumed a new form, Cross-Z Evol, the fusion of his and Evolto's powers, later gaining the upper hand against him, and destroying him and the reconstructed Pandora's Box except for the original White Pandora Panel.

Killbus has a hedonistic personality and seeks pleasure from destruction, which led to the destruction of his own planet. He wishes to use the Pandora Box to destroy the entire universe, even willing to die along with it. He does not show any type of sibling care for Evolto, even willing to kill him just so he can have the Pandora Box all for himself.

Killbus seems to be more attracted to Satoshi Kakizaki, opting to take his appearance instead of the geeky Sento Kiryu.

Powers and Abilities

 * Hazard Level 3+: Killbus has a Hazard Level of at least 3, as shown by his use of the Build Driver. However, his Hazard Level is likely to be at least 5+ due to him being a member of the Blood Tribe and besting Evolto in battle. Throughout the film, he effortlessly defeats Ryuga, who has a recorded Hazard Level of 7, implying that Killbus may also have the same Hazard Level as well (or higher).
 * Liquefaction: Like Evolto, Killbus can become a teal pool of liquid for transportation purposes.
 * Venomous Tentacle: Killbus possesses a tentacle that he can use to inject his opponent with dangerous venom. This can be countered with the Genius Fullbottle.
 * Shape-Shifting: While his true form has not been revealed, Killbus can mimic any human due to being a member of the Blood Tribe. He first took the form Sento Kiryu before settling on the appearance of Satoshi Kakizaki.
 * Infusion: Killbus infused Sento's pet spider robot with his own genes in order to create the Killbuspider.
 * Fullbottle Creation: Killbus created the Killbus Spider Fullbottle using his own genes.

Trivia

 * TBA