Board Thread:Theories and Speculation/@comment-30241447-20180715175819/@comment-4974066-20180715210313

Well, how do people learn things in the series? Seems to me like there's 4 options: Have a tradition passed down to you orally (like Hiden/Secret jutsu), Have someone personally train you/bestow it to you (like how Kakashi taught Sasuke chidori/Hagaromo giving Naruto and Sasuke his powers), Have the ability in question 'awakened' (like a KKG), or learn about it through some text (like how Suigetsu discovered the Dead Demon Seal: Release/Sarada learning how the Sharingan works (anime)). Tobirama and Minato obviously were not alive at the same time, so option 1 and 2 are out. FTG isnt something you awaken so option 3 is out. That only leaves option 4. It's probably more likely that theres some scroll/text that has instructions on how to do FTG. Even though Minato did try to personally teach 3 other characters how to use it despite them only being able to use a weaker version of it, it makes sense that the intricacies of certain jutsu (especially powerful ones) are written down for later generations. I think the D4 touches on that subject...somewhere.