top (by battery terminals) portion of positive wires are actually fusible links (originals on my car are Yamazaki FL1.25) and are joined, I believe with crimp connectors, with the main harness wiring which goes toward the main fuse box (from there it goes around the engine bay, fans, fuse boxes, AC, alternator, lamps, fogs and such).
what you need to do is to remove the battery and the air box. then remove the insulation material (could be the plastic tube or electrical tape or so) from positive wires until you find where they interconnect with main wires, they will look weird at that spot, like broken or bent, because there is a crimp connector there. there will be heatshrink wrap over the connection point on each of wires.
It will be before reaching the main fuse box for sure. the junction could be actually at the plastic arm where they are all attached to. this is the point from where the starter positive wire goes to starter assembly.
I can look for a pic to show, you, I replaced one section of positive wire before (leaving old terminal which I re-used). should have a pic or two.
EDIT:
here's a thread with some pics where I was working on it (old harness of my V6, replaced it eventually):
1mzfe / A541E @ 122k miles, p0500, p1135, p1155
it seems the connection you need to replace the positive terminals, is no farther than 5-6 inches from the terminal.
if your battery positive wiring kit is longer than that, maybe you should replace them all at the fuse box? it's a bit a pain in the arse to remove fuse box, all wiring is tight under it, need to peel the fender liner off, detach some clips and such.