This study presents features of SAKURA, issues identified, and modifications made during operational trials. SAKURA enables learners of Japanese to practice writing email from beginner level and up. While developing SAKURA, a "Data Collection System" was used to collect basic data from 16 email tasks at beginner and intermediate levels. After developing SAKURA, the basic data was used to extract a "Mistake List" and "Essential Expression List". These lists were added to SAKURA when conducting operational trials. Names of advice types and classification criteria were modified to match the learner’s Japanese ability.
https://ror.org/03zyp6p76 
