Dear Chiharu,
I am glad to know that you have found my feedback helpful.
I acknowledge your passion and commitment towards your tennis despite the set backs.
I recommend you to practice the following drill for improving your flat serve.
Give it a go and I look forward to seeing your next set of videos.
Regards,
members.tennisevolution.com
Flat Serve Level 1 Progression (1/2 Serve) | Tennis Evolution
Flat Serve Level 1 Progression (1/2 Serve) | Tennis Evolution
Herman Krackow,
Head Coach