^If there arn't any survivors, it won't be imprinted in the genes of future generations. If these ones got let go, their spawn would know that home invasion gets them fucked up six ways from sunday.
^ Exactly. If the Yukkuri are kept suffering and unable to take it easy for a long time, "home invasion does not let you take it easy" would be imprinted into the Yukkuri genes, much like the innate fear of factory and the successful breeding of constantly-crying types and non-shitting types.
In the end, Marisa and her family just ended up asking for forgiveness without realizing what they did wrong. It's not a problem to just kill them outright, but then it's not interesting...
Thinking about this, Oniisan took out an old and seldom used terrarium and put the shithead family inside for starters.
"Yu!!! This place is too cramped!! Hurry and let us in the house right now, ze!!"
The shit-filled manju kept calling, but oniisan ignored them and tossed in some raw trash after a little while.
"Yuuu!!! It smells, ze!!!" "Can'd dage id eajy!!!" "Shitty grandpa hurry up and let Marisa and her family out of here!!! Reimu hates smelly trash!!" ".... starting from today, you're the compost heap. So hurry up and eat the garbage." "What did shiddy grandpa shay!? There'sh no way we can ead thish!! Are you shtoopid? Wand choo die!??" "Shiddy grandpa can ead thish himself!!! The cude-cude Weimu and her family will dage id eajy in the big house!! Shiddy grandpa bring shweet-shweets!!! Weimu will become angwy!!!" "I don't care if you don't eat it. I don't plan to give you any other food, so just go starve to death in that corpse-stink filled terrarium."
Saying that, Oniisan went back to the house. Oniisan will first shatter the pride and the holier-than-thou attitude of the shit-yukkuris by humiliating them with the compost heap.
"Yubu.... id sdinks..." "Can'd dage id eajy like this!!!" "Little ones, hang in there..." "There's no way Weimu can endure thish!! Weimu wands choo ead mishder shweet-shweets!!" "Yu!! Go beat the not-eajy Kimemaru!! Then bring the cude-cude Mawisha into mister house!!" "Why would you say..."