How Did Kakashi Get His Sharingan?
Everyone knows how brutal a war can be in the real world. Much else in a fictionalized Earth setting wherein humans are born with innate talent to control the mysterious elemental powers of chakra. Every war in the Narutoverse claimed tens of thousands of lives, be it shinobis or ordinary citizens of every village. In the Third Shinobi World War, a Ninja named Kakashi Hatake, a non-Uchiha, received the powers to wield the mighty Dojutsu Kekkei Genkai known as Sharingan.
Kakashi, got his Sharingan from Obito Uchiha during a mission to cut off the supply line of Iwagakure by destroying the Kannabi Bridge on the Third Shinobi World War shown at Episode 120 of Naruto Shippuden series. They were ambushed by an Iwa-nin with Kakashi getting his left-eye badly damaged and Obito crushed by a large boulder in the process. The Uchiha then decided to gift his Sharingan eye to his best friend Kakashi which Rin Nohara, a medical Ninja, transplanted it onto him to confront the remaining Iwagakure Shinobis.
It was quite the tragic event for our prodigy who was just promoted into a Jonin, where he lost two of his teammates in the very same day. The Sharingan that Kakashi got was also quite the boost in his prowess as his newly invented technique called Chidori, where he was finally able to handle the speed. But that wasn't a worthy trade off for Kakashi. Minato finally tracked the team down but noticed only the two of them remaining, with Obito Uchiha missing. Albeit the loss of a teammate, Team 7 still did their mission and destroyed the Kannabi Bridge and returned to Konoha to mourn for the lost Uchiha's life.
How Did Kakashi Get Mangekyou Sharingan
Did Kakashi Lose His Sharingan?
Yes. Kakashi Did Lose his Sharingan. It was more like it was snatched from him. To obtain the powerful Rinnegan, Madara needed to snatch Kakashi's eyes, which the original owner was Obito Uchiha. This was also the very episode about Madara's plans were revealed to the fans and how it was all according to the weaved events he personally entwined for decades of thorough scheming.
Every fan knows how taxing Mangekyou Sharingan is for the user. That's why Madara needed the eyes of Kakashi Hatake to restore his vision and also to reawaken the Eternal Mangekyou Sharingan in the process. Due to this, he was able to upgrade and stabilize his Susanoo further and weakening a strong shinobi (Kakashi Hatake) for the upcoming war.
Does Kakashi Get His Sharingan Back?
Not just one Mangekyou Sharingan, but two! Albeit temporarily, Kakashi got his Sharingan Back on the fight with Kaguya, Obito sacrificed himself to protect our protagonist duo Sasuke Uchiha and Naruto Uzumaki, though his body dies, his spirit was intact and resides on Kakashi Hatake. This led him to gain two Mangekyou Sharingan "temporarily" as fueling those taxing Dojutsu Kekkei Genkai was Obito's remaining mana. After the fight with Kaguya, it was lost forever. Or is it?