:I admit the opening is not very well-written at the moment, but: (1) the article was originally clearly about Teika's collection; (2) most of the article below the first paragraph (5/6 of the sections) discuss Teika's collection exclusively; (3) it is fair to assume, then, that almost all of the edit history relates to Teika's collection, and needs to be preserved in a move; (4) when the word Hyakunin Isshu is used in both English and Japanese, 99.9% of the time it is being used as shorthand for the Ogura Hyakunin Isshu; and (5) all of the other hyakunin isshu are explicitly parodies of or inspired by Teika's collection, and are not individually notable enough to be discussed in a separate article (they should therefore be given a subsection of the article Ogura Hyakunin Isshu).