One of the important factors in learning Japanese language is to master the Japanese characters, especially hiragana and katakana or often called as kana.􀀁 Basic Japanese language learners especially high school students are often facing the same problems as they starting out in learning kana letters. Based on this, researchers want to help students in learning kana letters by using a flashcard as a media called kartu kana "AKAITO". The researcher chose kartu kana "AKAITO" as a media because it contained materials that the students needed to learn the kana letter. This study aims to determine the effectiveness of kartu kana "AKAITO" to help students of class X in SMA Negeri 4 Yogyakarta improving the mastery of Japanese hiragana letters. The method used on this research is experimental research, where data obtained by giving test in the form of pretest and posttest, and given questionnaire to the respondents. The alternative hypothesis in this research is proven, which means that the use of kartu kana "AKAITO" is effective to improve the ability of mastery hiragana letters to students of class X in SMA Negeri 4 Yogyakarta academic year 2017/2018. In addition, students' responses of using kartu kana "AKAITO" as kana learning media are also very good, its effective to improving the mastery of Japanese hiragana letters. I`m suggest for the next research aims to determine the effectiveness of kartu kana "AKAITO" to help students improving the mastery of Japanese katakana letters or vocabulary.