Lunge Storage is a technique which stores the forward displacement Link gets from a forward sword stab attack, by cancelling the attack early. That displacement will then be added to his next attack with a sword or deku stick. Lunge Storage is mainly used to increase the distance of a jumpslash, enabling certain acute angle clips that are not possible with a normal jumpslash.
The originally discovered method of Lunge Storage requires the use of a ledge. After climbing a ledge, hold Z, then press B and hold up on the control stick at the same time to perform a forward lunge attack with the sword. Link will start the attack but it will be cancelled by him falling off the ledge backwards, setting up Lunge Storage. Once Lunge Storage has been set up, you can simply press B and Link will lunge forward the same amount he would have from the earlier cancelled lunge. Lunge Storage is cancelled once the lunge has been used, so you have to set it up each time you want to use it. Lunge Storage also increases the distance a jumpslash travels, which allows clips through certain acute angled walls that cannot be clipped through with a normal jumpslash.
Lunge Storage can also be achieved by taking damage at the right time of the forward lunge attack animation, shown in the video below.
Lunge Storage can be used as an alternate method of Door of Time skip, and is generally considered to be easier than the normal backwards sidehop method.
Lunge Storage is useful in Ice Cavern to skip the three barriers in the spinning ice blade room without Blue Fire or explosives.