Yuko was looking for aizen with her butterflies. This chaos, she believed he didn't just die yet.
That's when...
She saw aizen through her butterflies at Central 46. She then saw toshiro come in and got shocked by what he saw. That aizen was still alive. But before toshiro could even really confront aizen he got defeated by aizen and aizen teleports. She tries again to find aizen with her butterflies.
" Toshiro. Daijobu?" Yuko speaks through the butterfly.
Toshiro:Yuko... Aizen...
Yuko: I know!!
Unohana: he'll be fine. If you have butterflies everywhere now, do you know where aizen is now?
Yuko: ah... I just found out. Execution ground. In front of me.
She watched as aizen take the hogyoku out of rukia.
Aizen: you've been watching me for so long. And yet you're still not one step ahead of me. Hirako Yuko. You're not like your nii-san at all.
She couldn't rebut at all. He was right.
Aizen: too bad you've exhausted almost all your reiatsu. If not maybe you could put up a fight with tousen or gin.
All the officers gather around the three captains. That's when the menos light came and took the three of them away.
She could only watch...
Aizen: I will sit in heaven.
Yuko: so you're going to be god
Aizen: if that's want you want to think.
Yuko: then we'll be god killers.
Aizen: I'll be waiting.
The gap closes and the three captains had left.