Reionics: I Have Tons of Obscure Monsters

Another familiar transmigration story, another familiar no-System setup. He starts with a single Battle Instrument, and everything else depends on grinding, in a character-building adventure. He begins with a Geronimon. Watch how the protagonist, Lei Ge, survives in the Ultraman universe. A few details about the setup: multiple female leads, with Dark Zagi as the main one. Feel free to suggest the others in the comments. No System, just a Battle Instrument, a space-time teleportation card, and a time barrier that shields him from the rejection of the greater universe. The protagonist's style will gradually become more like Wang Xiaoming's, but he absolutely won't become a eunuch.