I found out I mess up the order....

That's because posts that has more than 1 child will be automatically sorted by upload date.
You can solve this kind of problem by creating pool.

The artist also compiled it into one post on nicoseiga.
http://seiga.nicovideo.jp/seiga/im5531256

Wait a second i do remember that kashima seiyuu is kayano ai not sakura ayane

yunashiku said:

Wait a second i do remember that kashima seiyuu is kayano ai not sakura ayane

Yes, Kokoa's oneechan is Kayano Ai

Seika said:

Yes, Kokoa's oneechan is Kayano Ai

that's not what i mean at first this post tagged sakura ayane before it got changed to kayano ai. that's why i confuse at first