The trainer is a minor character in Season One and Season Two of Sense8. He has known Sun Bak for quite some time and trained her at a young age to defend herself as well as fight in a martial arts tournament. Though her father did not approve of her fighting, she continues to train and develop with her trainer, entering fights underground.
When it came to a decision to take the blame for her brother's crime, Sun visits her trainer and gives him her dog Jindo, which he takes care of while she is in prison. She returns to him in Season Two to take shelter from police and continue training before her future battle with Joong-Ki. While she has no plan, she tells him that she only desires his death or will die from trying.
After being visited by Detective Mun, Sun decides to leave her trainer and Jindo, hoping not to stir anymore trouble for those close to her. He gives her a bag filled with clothing, food, and money for her to utilize in her travel.