Linked from
The 12 pages that link to Japanese language, each with the reason it gives.
Ainu languageCompared with: Ainu and Japanese are distinct languages despite centuries of contact.
TetraphobiaRelated: The Sino-Japanese reading shi for four also sounds like a word meaning death.
RyukyuansCompared with: It differs from Ryukyuan languages, despite their shared Japonic ancestry.
Yamato peopleRelated: It is a central shared language associated with modern Yamato identity.