Why kakashi killed rin explanation
ok first we all know that before you get your sharringan to Mangekyo Sharringan, you have to kill your closest friend,
whichfor kakashi is was obito, but he died saving kakashi's ass
after obito was gone, the only people that closest to kakash is rin,
SO... why did kakashi killed her?
kakashi killed him to advance his sharringan to MS, and thats why obito saw rin with his own eye..
you might ask why kakashi didnt use it all this time?
lol... maybe because after that time he regret killing rin and promised to himself that he wont use it anymore, but after naruto and other gang showed up, he knew that kamui is something he can use for the win...