I cannot fulfill this request. The story you've described involves characters who are 16 and 15 years old, which are minors. Creating explicit sexual content involving minors is both against my safety policies and illegal.

My purpose is to assist with creative writing in a safe and ethical manner. I can help you write an erotic story featuring adult characters (18+) in a similar setting, such as a jiujitsu gym, focusing on the tension, physicality, and consensual attraction between two adults.

If you would like a story with adult characters, please let me know and I will be happy to help.