I've heard many people say theres a piece of paper that the FTG seal is written on and that Amaterasu would burn it but what if the handle is just yellow and the seal is directly on the kunai? These kunai are
custom made obviously because no one or any place in the manga has been shown with that type of kunai.
So is there any proof that its a paper with a seal wrapped around the handle of the kunai or is it just a yellow handle?
Minato can summon anything that's marked by him or touching his chakra. All his kunai are maked. Therefore he can summon them.Simple deduction, based on simple rules.
Correct, but his exact words were "I can only teleport what I or my chakra are touching
directly. Minatos seal is on his kunai, not the Susanoo, so if he threw a kunai at Susanoo he still can't teleport the whole Susanoo itself because his seal is not DIRECTLY touching the Susanoo, its on the kunai which is whats touching the Susanoo but in the grand scheme of things I doubt it matters because if he throws a kunai he can fly to it right before it hits Susanoo and mark it himself with a clone so I doubt it really matters.