Prompt to start with:

<lora:Millium-10:0.8>, Millium Orion, blue hair, short hair, antenna hair, ahoge, yellow eyes,  flat chest,

black hat, headwear,

black and yellow vest, white shoulder armor, zipper,  white shorts, black thighhighs, green belt, white boots, 

It usually tries to generate the hat even if you don't prompt for it.