Seiji Fukushi, Hirona Yamazaki and others have been reported to appear in Kamen Rider Zero-One the Movie! These new characters excluding Hirona Yamazaki's character are going to transform into soldiers called Kamen Rider Abaddon. The people who are going to transform into Kamen Rider Abaddon have a Humagear Tattoo on their face, so I assume they could be Humagears, but without the Humagear Module.
They are going to use repainted Slash Riser and Shot Risers to transform into Kamen Rider Abaddon.
According to Wikipedia,
The Hebrew term "Abaddon" (Hebrew: אֲבַדּוֹן Avaddon, meaning "doom"), and its Greek equivalent "Apollyon" (Greek: Ἀπολλύων, Apollýōn) appear in the Bible as both a place of destruction and an archangel of the abyss. In the Hebrew Bible, abaddon is used with reference to a bottomless pit, often appearing alongside the place שְׁאוֹל (Sheol), meaning the realm of the dead.
Hirona Yamazaki is going play the role of play the role of a researcher named Akane Tono who meets Aruto in the movie. It's not known whether she researcher of Humagear or something.
She is going to appear in Monster Hunter movie releasing in 2021.
Seiji Fukushi is going to play the role of Bell. He seems to lead the Kamen Rider Abaddon army. He has Red Shoulder pad with wires.
You might remember Seiji Fukushi from Live-Action PATLABOR. He had revealed that he used to watch Kamen Rider in his childhood and he had taken Kamen Rider audition at the beginning of his career, but had failed. The auditions which he took could be for Kamen Rider Ryuki, Kamen Rider 555 or for Kamen Rider Blade considering the year when he started his career.
Mei Hata is going to play the role of Moore. Her Kamen Rider Abaddon Shoulder pad & wire colour is Silver.
Yuu Oyama is going to play the role of Lugo. His Kamen Rider Abaddon Shoulder pad & wire colour is Black.
Japanese Pro-Wrestler Hirooki Goto is going to play the role of Buga. His Kamen Rider Abaddon Shoulder pad & wire colour is Orange.