[Khu]

yay another question about IW.

Someone link reply pls.

Otherwise:

Spoiler for Bleurlfhlkajd:

Illusionary World: Basically Ushio and Tomoya, you realise that right?
K.
What happened in Illusionary World/episode 22:
Tomoya got sent back to the real world, 5 years ago i.e. Ushio's birth.
Why Nagisa was so frail:
GO WAY WAY BACK TO CLANNAD.

Akio says that he WISHED Nagisa to live when she had a cold.
It's hypothesied that from that Nagisa's life was tied to the IW. When Nagisa died, it was passed on to Ushio. Because of this tether to the IW, Nagisa was always pretty frail, as the IW required her life to sustain itself.