We have developed a menu-selection-based Japanese input method for a pen device. To obtain user-input kanji-form text rapidly, the system requires sequence of consonant. Following this, the user selects kanji-form candidates inferred by the system. In some situations, consonant sequences can trigger an explosion of kanji-form candidates. Therefore, we have implemented a method for reducing candidates through vowel fixing. The user can input consonants, and select kanji-form candidates fluidly, using FlowMenu.