My coach is refusing an insurance payout for a life altering injury. What can I do now?

5 months ago, I received a concussion and whiplash injury from a kickboxing class and it has prevented me from working since. Near the end of the class, the coach gave us an exercise to allegedly help us keep our eyes open while being punched. She instructed us to stand opposite each other and to take it in turns throwing hooks as hard as we can at the other while the other just took it without dodging. All of this without headgear. I was very hesitant to do it but the coach insisted it would be fine. It was also only me and one other person that class so I went along with it to not hold the class up. I went to the hospital same day.

During these last 5 months, my life in Japan has been extremely difficult. I live by myself so dealing with an injury like this has been overwhelming which is why I only started pursuing a claim now. My coach acknowledges my injury but says that they can't make any insurance payouts because of it, and didn't provide any explanation or details. Is my case hopeless then? Is there anything I can do?

Update 1: Wow thank you for the support everyone! It really means a lot! The communication has intensified but I've been able to confirm that they didn't have insurance. So their avoidance and defensiveness makes a lot more sense.

by ghotiofthedeepbeyond