1girl, 6+boys, blush, brothers, brown_hair, dt.calico, happy_birthday, heart, heart-shaped_pupils, long_sleeves, looking_at_viewer, male_focus, matsuno_choromatsu, matsuno_ichimatsu, matsuno_jyushimatsu, matsuno_karamatsu, matsuno_osomatsu, matsuno_todomatsu, multiple_boys, osomatsu-kun, osomatsu-san, sextuplets, short_hair, siblings, symbol-shaped_pupils, wall-eyed