Summary: Pregnant Reimu calls for her owner, and he initially thinks that Reimu is going to give birth, but actually she just needs to poop.
As he carries her, he tells her of his hopes that this child will be good and well-behaved, but Reimu just passes it off as stupid talk, since her child will be easy. However, as she's trying to push out the poop, she starts to give birth.
Anon tosses in Mecha Reimu, and tell Reimu that she has twins. By stressing over the fact that Mecha Reimu and Komarisa are her children, Anon gets Reimu to believe him.