This paper analyzes writing tasks in academic writing textbooks for Japanese university students, focusing on the organization and difficulty of these tasks based on the Common European Framework of Reference for Languages (CEFR). A total of 411 writing tasks from 30 textbooks were coded by two experienced Japanese English teachers. The author identified 13 tasks that appeared most frequently for further analysis. The study involved 208 Japanese university students who completed these 13 tasks without the use of dictionaries. The same two teachers then evaluated the students' written responses. The aggregate scores from the analytical assessments were examined using Rasch analysis to determine task difficulty. The findings indicated that textbooks for Japanese university students emphasize rhetorical functions such as explanation and narration, while showing limited integration of other language skills. Textbooks should aim to achieve a more comprehensive balance, aligning better with the CEFR framework. By examining how textbooks sequence rhetorical functions and their alignment with task difficulty, the study aims to provide insights for developing more effective teaching materials.