Horror and romance... Ok, let me see...
Ookajira could be tired of the terror that surrounds his species, and is doing his best to find his place in a world that doesn't want him, humans and kaiju alike. He could meet a love interest or two along the way.
But there would be something haunting him. In the shadows, fast, mysterious, lethal. Something that pursues him, in vengeance for the bloody legacy that Godzilla left behind, falling over Ookajira by proxy of belonging to the same species.
What do you think?