Aww why does heir or air matter? Japanese translate into English can have problems like this all the time ;x
To redirect the direction I guess I'll post the summary of book 12.
Spoiler for Summary:
Crow fights cerberus. cerberus' left shoulder starts to talk like a different person. Crow grew impatient and pressed on with the attack on cerberus. He chose to hit the left shoulder that opened up because he thought that would be a weak point but he ended up planting his forearm into cerberu's mouth. To prevent cerberus from chewing his forearm right off crow flew up so that if cerberus does indeed chew his arm off he would fall and die, but cerberus did anyway and revealed that the 2nd head can copy enemy's ability with duration proportional to the amount of body part consumed. So cerberus floats in the air with the copied wings then talks about his mission as to equip chrom disaster then the times up and he fell to his death
Bell found some enemy that shoots laser invited crow to go with her to train on theoretical mirror, and they bumped into chocolate puppeteer. They learned from her that the enemy they were going to fight was her pet and that she's protecting the pet from her friends who were were forcefully infected by ISS. Crow being a chump that he is decided to help choco getting her friends back and offered to help choco getting her friends back. Magenta scissor then showed up with choco's friends mint mitton (parent), plum flipper (child) and a gigantic avarcardo to nab choco. While crow fight magenta scissor choco got eatten by the avarcardo and in dire need of help. Crow tells choco to call out her friend and redirected the laser blast from the carbuncle to melt the avarcardo, saving choco from being a dessert and in the process learn optical conduction. Bell then reversed the infection wit citron call and the 3 friend reunited in tears.
Magenta then retreats with avarcardo, leaving them 2 ISS kits that are no longer usable. Crow brings the kits back to NN and they all looked at it and saw the emblem of RR and that forces Lotus to tell us more about RR.
Just when Lotus finished telling crow about her evil sister and how RR died, they entered into battle royale mode started by cerberus with Lotus being a spectator. Crow fights cerberus and lectures him about bro love, bromance, bonds and stuff like that. Moved by crow's talk but before he could do anything argon array showed up with her lasers and starts raping cerberus, telling him who's the boss. Just before array could land a killing blow, diamond queen, err I mean aqua current (her watery armor has ice cubes in them making her look like diamond queen) showed up and interrupted the fight telling array that loosing to a lvl 1 will cost her a lot of points.
In the author's comments he said something about aqua returning as a regular character in the next one and that one more girl is added into the mix