LOL there's no way Jiraiya is Naruto's Grandfather. That is just WAY too farfetched. Minato's history is just a mystery
Sound's like you've got a good plot for a Korean Drama version of Naruto where Naruto finds out his perverted teacher is actually JIRAIYA. Plus if Jiraiya hooked up with tsunade and tsunade had a kid... and happened to be Minato... Poor minato LOL where'd he grow up? in an orphanage?