[X] Try to teach him by integrating him into teamwork, where… if he can be made to stop doubting himself quite so much, he can see that he plays a part in such a fight.
[X] It's time for a training expedition… at least, a short one. Go out into the desert, see if he can't do a little better without people to compare himself to.
[X] Music! Give Yuichi various matching background music during training to boost his spirit. It's just like in some of those ninja movies, but in real life!