Hi Chiharu,
Please click here to review my analysis of your forehand. The footwork lessons recommended to review are:
https://members.tennisevolution.com/topics/crossover-shuffle/
https://members.tennisevolution.com/topics/high-down-the-line/
https://members.tennisevolution.com/topics/cross-behind/
Best,
Herman Krackow,
Head Coach