1boy 1girl armlet armor bangs black_shirt blonde_hair blue_eyes blush bracer breasts brother_and_sister castor_(fate) collar covered_navel diadem fate/grand_order fate_(series) faulds gradient_sky halterneck highres looking_at_another medium_hair metal_collar night night_sky open_mouth pauldrons pollux_(fate) purple_sky robe shimi_to_ufu shirt short_hair shoulder_armor siblings sky small_breasts smile star_(sky) starry_sky sunset twilight twins white_robe