Oh, here's how to get graphics for PC Neptunia working for Vita. However this will require you to do a little hex editing. If you do not want to do that, just don't bother.
Anyway, the TID Tool included with Kitserver is sort of messy so it will not produce a file that is compatible with Vita. The first picture is a fresh TID from the Rebirth 3 logo for Vita. The second picture is a slightly modified logo that used to be a TIFF file, that's been returned to the TID format.
Anyway, you'll see two changes right away here. First, the fourth hex address (0x03) in the Vita original has a value of 92. In the Kitserver TID, it's 90. If the value is not 92, the graphics file will not load on a Vita. So, change it to 90 and save.
However, if you put it back on your system, the colors will look bad. This is because a byte of empty space (empty space = address value "00") from before the part where the graphics data actually begins (with all the "FF" values) is moved to the very end of the file, which causes the alpha and color channels to get screwed up.
To fix the bad colors, add a whole new "00" byte to a point just before hex address 0x80 (0x73 works good). Now go to the very very end of the file, and if there's a "00" there, completely delete and remove that byte from the file.
Save, and load onto your Vita. You should have perfectly functional Vita graphics now. At the very least, this will work for changing the game's logo. You might have additional difficulties working with other textures.
Note that if you work with PNG files and not TIFF, all the "FF" values will disappear. Those are not important for the functioning of the graphics, although they are a good way to see where the graphics data begins. Just do what's instructed, ignoring that one difference, and you will be fine.