To provide an arrangement of keys for vowels and consonants that makes possible the efficient input of romaji(roman letters) for use with hardware such as a mobile (cellular) phone in making e-mail.

A keyboard arrangement is made as in Figure 1 so that any input of kana (a letter of the Japanese syllabary) causes the thumb's movement to be centered on the middle row where all the vowels are located, thus eliminating redundancy in the movement of the thumb and making possible the quick production of e-mail.