Yui told Kirito that it would be a good idea for him to clear out his inventory as all the items were bugged and he could be detected by the system if they remained. As he was about to, he was hesitant in doing so. I can assume one of the 2 reasons:

  1. All the items were a record of his 2 years in SAO and had a personal connection to them.

  2. Yui's Heart was in the inventory and he was being careful not to delete it.

However, in the anime, it didn't show any sort of filter was applied and his entire inventory was cleared. So I am wondering what happened to Yui's Heart - was it not in his inventory because Yui was right beside him or was Yui protecting it in some way from the system so that it wouldn't appear in his inventory.

  • 3
    I'm assuming she was no longer in his inventory because she'd been "unpacked" into the gameworld again - she didn't exist as an item in inventory, so thus could not be removed (I don't have a way to check this though). ...As much as I liked that show, the levels of Hollywood Hacking some of the plot elements would require is a bit painful. Mar 26, 2014 at 0:25

4 Answers 4


Kirito saved Yui's data inside his NervGear local memory. The program is usable in Alfheim Online, and it didn't get wiped out, maybe because it wasn't data from SAO's save data (like his items). If ALO is based on SAO, then many interface programs are just the same. This is shown when Kirito starts at ALO and first checks the Logout button (which is there, unlike SAO).

Maybe the inventory showed both the items from SAO and Yui's Heart from the local memory. When he wiped out the inventory, Yui's Heart remained because it was not a cached item.

  • SAO and ALO actually have the same game engine... "The Seed".
    – Gerret
    Apr 4, 2015 at 10:31

From the point of view of programming and my experience (regarding MMO mechanics), I think the Yui's Heart item is like an object who grants a passive skill in ALO.

When Kirito activated it, Yui became bound to Kirito's character so all data from Yui's Heart were also transferred.

From Sword Art Online Volume 3 – Fairy Dance - Chapter 2:

“So…wait a second”

I suddenly thought of a possibility.

If these are the items from Aincrad, - then «that» should be here too. I touch the item window, and scroll down the menu with my fingertip.

“Please, please, please be there.”

I quickly scroll down the list, ignoring all of the gibberish. My heart started beating faster and a feeling like ringing bells resounds through my body.


My fingers unconsciously stopped. Below my finger was a line of letters like all of the others save it was emitting a warm green color. «MHCP001».

Almost forgetting to breathe, I touched the name with trembling fingers. After selecting the item, the color reversed. Moving my fingers I pressed the button labeled “Use Item.


Like your previous question, I don't think there's a way to confirm exactly what happened here, but I have 3 possible explanations.

  1. Yui's Heart was marked as a special item and couldn't be deleted (e.g. Quest item, etc.), but I think this is the least likely, since as you said, the anime showed his inventory being empty and there was no filter on it.

  2. It could simply just have been consumed when Yui was summoned, so it was already gone when he deleted everything.

  3. It was simply deleted. Since Yui was already initialized in the world, it didn't matter if he had it in his inventory or not.


One other explanation from a developer perspective is that when Kirito supposedly saved Yui's Heart to his NervGear, it would have been stored in a different physical location from his inventory (which would typically be stored server side).

The persistence of one's SAO inventory would make sense if SAO and ALO used the same infrastructure, I have a feeling they may have been the same but could not say so with certainty.

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