Ryūha 流派
Japanese word for a school or lineage within an art, craft or martial art, set apart from others by its method, style or principles.
Ryūha is the full noun for “school” in the sense of a lineage. The Daijisen dictionary defines it as each line within an art or craft that is distinguished by its own method, style or doctrine, and the Nihon Kokugo Daijiten extends this to the performing arts and martial arts. Heibonsha’s Jitsū glosses it simply as a style or school of practice.
Wikipedia explains that the suffix ryū, which appears in the names of individual schools, is used in the sense of ryūha. The noun therefore names the idea of a school or lineage, while ryū attaches to a particular one.