Re: Injury and Responsibility
On my second introductory lesson when training ikkyo I was uke and landed with my chest on my fist. I think I broke a rib then, but I didn't have it checked (they wouldn't treat it anyway). Luckily it was the last lesson before summer break, so it had 6 weeks to heal before lessons resumed.
I estimate that about once a month there is some blood on the mat (once in 15 training hours with 15 people on the mat on average). The "victim" is usually wearing a hakama (2kyu and up in our dojo) and treated with some adhesive bandage. Like yesterday evening when a hand was punctured with a tanto while training tanto chudan tsuki.
I haven't seen more serious injuries yet.