>>66216058chou 長 means leader, dan 団 just means like, group of people. Maybe troupe-y vibes.
marine's houshou pirate crew is a dan, 宝鐘海賊団
the sakura wars song marine always sings teikoku kagekidan refers to a dan, 帝国華撃団
the spiders in marine's beloved hunterxhunter are a dan, 幻影旅団