Cult: Kugai leads one called the Black Bodhi Tree. Specifically, he brainwashes them with copies of his Zakuro Lockseed and turns them into suicide bombers.
Aside from that, his use of the Genesis Core in place of an indicator faceplate to harness and combine the power of two Lockseeds at once chronologically predates Kōta's first use of the Jimber Arms forms, and uses nearly identical mechanics.
Dual Wielding: Saver uses both the Saver Arrow and Bujin Gaim's Daidaimaru.
Evil Counterpart: Kugai is, to a degree, one to Kouta. Both wanted to save the world and became more than human, and both used an Orange Lockseed alongside another Lockseed at some point.
Far East Asian Terrorists: Kugai uses brainwashed innocent people as suicide bombers for his operations against Yggdrasil.
Fashionable Asymmetry: Saver's armor is notably uneven due to incorporating parts from two different armors, presumably.
Godhood Seeker: Kugai wants this, but he needs Ryoma's help.
Meaningful Name: Saver can also be romanized as Savior, both fit Kugai's vision of saving the world.
Not Quite Dead: Kugai twice. First after the experiment that went wrong, and then Takatora thinks he has dealt with him some way into the Gaiden. Ryoma knows better and presumably finishes him off for good. The novel reveals he's still alive.
Obviously Evil: Despite his claims of being a saviour, there's something to be said about the fact that Kugai uses the Blood Orange Lockseed, which has a transformation call roughly translating to, "Path of evilnote Ja no michi, on stage!"