A Difference of 1 Gender, 2 Species, 3 Places, 4 cm and 5 Years

Set in 3Z universe. He is male, she's female. He is an Amanto, she is a Kuro-Oni. He came from another Planet, she is from a different village and they are away from Home. He is 170cm, she is 174cm. He is 18, she is 23. He is Kamui, she is an obnoxious OC. That's not really much of a difference isn't it? Mary-Tsu warning. GinXOC, KamuiXOC...GinXOCXKamui!