sugimura tomokazu, 2k-tan, xp-tan, os-tan, 2girls, bare shoulders, black hair, blue background, blue eyes, blue hair, blue one-piece swimsuit, blush, bow, bowtie, breasts, calendar, character name, covered erect nipples, covered navel, crossed arms, december, detached sleeves, glasses, gradient background, hair ornament, juliet sleeves, large breasts, long hair, long sleeves, looking at viewer, maid headdress, multiple girls, one-piece swimsuit, open clothes, parted lips, puffy sleeves, rimless eyewear, robot ears, school swimsuit, see-through clothes, shirt, short hair, sidelocks, sleeveless, sleeveless shirt, swimsuit, swimsuit under clothes, taut clothes, taut shirt, upper body, very long hair, wing collar