My Head on your shoulders start

"Grandma, you want me?" said naruto, konoha's number one ninja. Naruto had gotten a message from tsunade and he and she wanted to talk to him privately about an important thing. "Ah naruto, you're here, good because I want to talk to you about an important discovery I made and an important project with it but let's talk about it later in my house." Said tsunade and the two left tsunade's office. Later, naruto and tsunade were at tsunade's home and her private lab, "so what is this big discovery?" said naruto, "naruto, I have discovered a way to expand human life and improve the human immune system" said tsunade, "that awesome grandma! How do you do it?" said an excited naruto, "well that is the part I wanted to talk about, you see for this to happen, two people must swap bodies via head swap" said tsunade, "what? But won't you die before you could do that?" cried naruto, "yes I know that but I invented a justu that allows to cut and preserve a person's head." Said tsunade, "so what does this have to do with people's immune system and life spans?" said naruto, "well the head stores cell from the original body of the owner, so when placed on the new body, the head not only makes the cells but copies the new body cells and DNA and combines them into new cells and DNA, making the person immune to dieses that would have usually killed them." Said tsunade, "wait, what about the justu the person knows?" said naruto, "well, your brain keeps all the information on the justu, so if you do it normally, your new body will do it, also your would learn the justu of the body's original owner." Said tsunade, "wow, grandma that is a great discovery, but why am I here?" said naruto, "well you are the first one to test it but it perment naruto, do you what to do it?" said tsunade, "sure, sounds like fun!" said naruto, "great! Here is the list of people to choose" said as she handed naruto a list. On the list was: sakura, ino, hinata, tenten, kurenai, temari, anko, shizune, tsunade. "Wow, a lot of these people are girls I know but who to choose?" thought naruto.