Search gender: all male female Masutoshi Name Meaning, Kanji Variations. 1 names found. gender: all male female Name: masutoshi Katakana: マストシ 0 Kanji: 増勤 Meaning: 増Increase 勤To work. To work under the guidance of an organization. To devote oneself to Buddhism. Practice. To make an effort. To love oneself. restraining oneself. You can save your favorite names with NAZUKE PON > About Japanese Names > Search For Japanese Names > Masutoshi Name Meaning, Kanji Variations.