As one of the more "recent" regulations, DD acknowledges political correctness:
(b) General. The disclosures shall reflect the terms of the legal obligation of the account agreement between the consumer and the depository institution. Disclosures may be made in languages other than English, provided the disclosures are available in English upon request.
The issue is discussed more frequently in terms of disclosures in Spanish, but the conclusion is always the same: You may, but are not required to provide disclosures in a language the customer can actually read. It seems a little silly to conclude that a consumer is "protected" by a piece of paper he or she cannot read. On the other hand, consider the effect if the law required that disclosures be provided in the customer's native language...
My guess is that your Japanese speaking customers will derive exactly the same amount of value from your disclosures as your English speaking customers do.
As John notes, there may be state law pronouncements. California is always a fertile field...