I'm guessing the parents tried to sneak another baby into existence.
TL: Only a scratch! Reimu, stay over there!Forgive me easy!*burp*
Yu...?Sounds like a baby's voice!Your little sister is growing inside Marisa!*The mammalian pregnancy in #9 taken care of
Stop it! You're hurting her!*A fitting time for removalStop squeezing! Stop squeezing!Ea... jy..*ripping*