Hatsu-yume is the first dream you have in the New Year. In Japan there is a saying: ichi fuji, ni taka, san nasubi, which means the luckiest dream you can have is of Mt. Fuji, the second luckiest thing to see in a dream is a hawk, and the third is an eggplant.
Musha-burui is that trembling with excitement, anticipation, and fear one has before engaging in a formidable task. It comes from the idea of a samurai going headlong into battle.