This time, she's been sending me these letters. One each week...

W-Wait, could it be...!

...Oh my, you've been getting weekly letters from Minamitsu-san as well? And they're themed around reincarnation? Exactly like Koishi's, then...

What does your sister write about?

It's styled after a theory regarding this novel "Dogura Magura"... the so-called 'fetus dream theory'. It's a peculiar book, but she really liked it.

The size and material of the letters is the same... The pen they used and the design on the back seem to match too...