At your level Hagakure is pretty much used only to reset sens between dungeons pulls (or before the boss comes back from downtime). When you obtain TsubameGaeshi however, it gets a whole new usage. To explain it shortly, in order to maximize your damage as a Sam you need to make sure you hit Tsubame on cooldown every minute. This means that you have to do a Midare each minute at the moment Tsubame goes off cooldown. Hagakure is used to do that, you basically eat your available sens (around 12 or 13sec before tsubame gets off cooldown if i remember correctly) so you can do your burst (apply Higanbana, do a Midare/Tsubame). So for now don't bother much with Hagakure, but keep that in mind when you'll obtain Tsubame.