[At least, Kamui knows if his body can still manage this, he isn't in any immediate danger, so he's just letting the blood do its thing and not minding too much if Fuuma just watches, murmuring to explain. He's probably never gone into detail about these things to you, considering the only other circumstances when a severe would like this happened to him, they were. not together, sob....]
If my heart isn't wounded or failing, I can still rely on the blood flow... like this.