Hagakure like some of the senpai already mentioned. It is used to filler combo. basically at high end content, we want to make sure our meikyo and gaeshi is always ready to use when cd finished. That being said, it is sometime difficult to manually judge when u can immediately use ur meikyo and gaeshi immediately when cd finished (eg, ur 3 sen is fully charged but gaeshi and meikyo still on a 8sec cd, then u're stuck whether to use midare, cause if you do then u need to rebuild 3 sen which normally take 16sec - 18sec)

And here is when hagakure play its part. normally depends on your skspeed. for me my skspeed is currently at 2.12, i need to control my gaeshi in exact 20-22sec to fully enter into hibangana opener then into burst window. so in order to do that i must clear all my sen b4 gaeshi go less then 20sec.

is basically just a number crunch. When u reached lv80 and understand hibangana and midare opener, then you will realize the use of hagakure.