1girl armpits bikini bikini_shorts blue_eyes breasts cleavage dutch_angle earrings goggles goggles_around_neck grin highres idolmaster idolmaster_shiny_colors jewelry looking_at_viewer lying medium_breasts medium_hair mitsuya_(mitsuya) navel on_back ribbon serizawa_asahi short_shorts shorts smile solo star_(symbol) star_earrings swimsuit water white_bikini white_hair white_ribbon white_shorts