1girl, ahoge, arm_behind_head, arm_up, armpits, ass_visible_through_thighs, blue_archive, blush, breasts, covered_navel, grey_hair, hair_ornament, hairclip, hand_on_own_stomach, hina_(blue_archive), long_hair, lying, on_back, one-piece_swimsuit, one_side_up, pink_eyes, reel_(riru), school_swimsuit, slit_pupils, small_breasts, solo, swimsuit, thighs, very_long_hair, white_one-piece_swimsuit