Campaign Creations

Hello!
I found the Avatar of Seiryu in the top left corner of the east district, in Book 6. I was able to reach and defeat him with Kurumi's Chaos Sentinel, but doing that way I wasn't able to collect the books that he dropped, because Hikaru and Kurumi can't reach the high ground where he stands. So, does anyone know how to lure him in a place where I can safely defeat him and collect what he drops?

They can't get up there. Certain other characters can, though.

I explored all the map, but I didn't find any other character. I'm missing something or I'll be able to return later to the district with other characters?

I solved the problem with the avatar of Seiryu, but now I have another one with the avatar of Byakko.
I found the gate that I must open to reach him. Hikaru told that the locking mechanism is probably elsewhere, and searching the map I found two levers right below the four guardians that I must defeat to complete the mission. I summoned a Juggernaut near the levers to activate them, but when I try to attack them it tells me that they are invulnerable!
So, is the locking mechanism activated by those levers (and accessible only in the future) or it's elsewhere and I missed it?

i'm not sure if you figured it out, but you need to first complete with Hikaru and then come back with Shizuka/Sorana and use the harpoon skill to reach them