1girl antenna_hair bikini black_hair blue_bikini checkered_background collarbone flat_chest grey_eyes hands_on_own_stomach highres idolmaster idolmaster_(classic) idolmaster_1 kikuchi_makoto looking_at_viewer navel nekopuchi open_mouth short_hair side-tie_bikini_bottom skinny smile sofmap sofmap_background solo standing step_and_repeat stomach swimsuit tomboy