>>36

(save-excursion
(save-match-data
(while (search-forward-regexp "[0-9０-９]+" nil t)
(if (> (- (match-end 0) (match-beginning 0)) 1)
(japanese-hankaku-region (match-beginning 0) (match-end 0))
(japanese-zenkaku-region (match-beginning 0) (match-end 0))))))

とか？