Toshiie tells Toshiro that he is Toshiro's brother and that their parents were killed by Aizen.

Toshiro: (prove it)

Toshiie: (Fine I will, Bankai Ginshin no Ikazuchiryu)

Toshiro: (Let's see if you can, Bankai Daiguren Hyourinmaru)

They both use every bit of power against each other and they both pass out.

When they woke up they were in Squad 4 because they were badly injured.

Toshiro: (I still don't believe you Toshiie)

Then they are called to a captain's meeting to talk about their new enemy called Akatsuki.

Akatsuki entered Soul Society to gain Soul Reaper powers and new members.

Itachi attacks Squad 3 /Squad 3 Captain is Toshiie Hitsugaya

Kisame attacks Squad /10 Squad 10 Captain is Toshiro Hitsugaya

Tobi (Madara) attacks Squad 1 /Squad 1 Captain is Yamamoto

Pain attacks Squad 8 and Squad 13 /Squad 8 Captain is Kyoraku and Squad 13 Ukitake

Konan attacks Squad 2 /Squad 2 Captain is Soi Fon

Zetsu attacks Squad 12 /Squad 12 Captain is Mayuri Kurotsuchi

Hidan attacks Squad 9 /Squad 9 temporary Captain is Shuhei Hisagi

Kakuzu attacks Squad 6 /Squad 6 Byakuya Kuchiki

Deidara attacks Squad 11 /Squad 11 Captain is Kenpachi Zaraki

Toshiie knew how strong Itachi was so he attacked him instead of sending his subordinates. All the other Squad sent their subordinates until they know how strong their enemies are. Toshiie knows Itachi uses Genjutsu so Toshiie uses his Kekkei Genkai called Wolf eyes which enhances his senses. It aloud Toshiie to see through Itachi's Genjutsu defeated Itachi. Itachi retreated because he wants Sasuke to kill him and Toshiie understood why.

Toshiro and Kisame's Battle didn't Last long because Toshiro Immediately went Bankai and froze Kisame when Kisame was about to fuse with his sword in the dome of water. Soi Fon made short work of Konan with her Suzumebachi. Byakuya sliced Kakuzu to shreds with his Bankai. Kyoraku and Ukitake took on Pain together and defeated all his bodies except the main body which stayed in the other world. They were also badly injured.

Zetsu was defeated by Mayuri and was made into a test subject. Kenpachi got bored with Deidara and let Yachiru defeat him. Tobi and Yamamoto battle lasted the longest because they were evenly matched. When Tobi noticed everyone else was defeated he retreated back to the other world.

Toshiro: (It's time for you to prove that you're my brother)

Toshiie: (One more battle then)

As soon as the battle starts, they both use Bankai.

Toshiie: (One way to prove it is to look at our Bankais they are the same except mine is Lightning and yours is Ice. And my Bankai seems to last longer than yours. So do you believe I am your brother now?)

Toshiro: (How could you know how long my Bankai last)

Toshiie: (Because when I was young had petals behind me that would disappear when I was in Bankai. So you must not have much time left since you only have three petals left)

Toshiro: (I'll defeat you by then)

Toshiie: (Let's see if you can)

They continue their battle. Then Yamamoto stops the fight

Yamamoto: (Toshiro, Toshiie is telling you the truth, he is your brother)

Toshiro: (Sorry for not believe you Toshiie, I'm glad someone in my family survived)

Toshiie and Toshiro protect each other from that day forward.