Disclaimer: Naruto does not belong to me. DO YOU THINK THAT IF I OWNED NARUTO THAT I WOULD BE WRITING FANFICTION!?
Ever since Naruto had successfully assisted in bringing Gaara back to life, one question had been a plague in his mind. This question was aimed at his sensei. The sharingan that Kakashi had possessed always seemed like a mystery to him. It gave Kakashi an edge in battles and had contributed to the survival of those who had battled the criminal organization known as Akatsuki. If Naruto had thought that his sensei, an outsider of the Uchiha clan having a sharingan was unique, than having a mangekyo sharingan seemed just plain out of the blue. The container of the nine tailed beast had recalled his former friend's words ever since Naruto discovered Kakashi's new ability. It was the same gift that had enabled Uchiha Itachi to slaughter Sasuke's entire clan. However, even with his limited knowledge of the sharingan, Naruto knew that the only way to obtain the mangekyo was to kill one's best friend. It was this fact that left Naruto with confusion and hope. Confusion, because as far as he new, Kakashi's best friend was killed by Iwa shinobi. Hope, because this might mean that Sasuke may be able to gain the mangekyo by other means. The curiosity of Naruto made him naturally want to get his sensei into telling him how he obtained the mangekyo. Curiosity that hasn't appeared since the former Team Seven had attempted to find out what their sensei had hidden under his mask. Suddenly a voice snapped him out of his musings.
"NARUTO! Are you just going to stare into space or are you going to eat your ramen so we can go home!'' yelled a very impatient Haruno Sakura. It all came back to Naruto now, where he was, who he was with, what flavor ramen he was eating, everything. Along with Sakura there was the subject of his curiosity, Hatake Kakashi, they were at, of course the Ichiraku ramen bar. Naruto made a mental note to badger his sensei into telling him about his new found ability, but for now decided on indulging himself on ramen, after he blushingly apologized to Sakura for being spaced out. After eating his meal, Sakura paid for her meal and left with a good bye, leaving Naruto alone with his sensei. Deciding to take advantage of this, Naruto approached Kakashi with the intent of asking the copy ninja about the mangekyo.
"You want to know how I obtained this new power, don't you Naruto" Kakashi said as more of a statement than as a question. The usually carefree expression on his face changed into a harder more serious tone. Before Naruto could speak, Kakashi interrupted "When Uchiha Itachi said that the only way to obtain the accursed mangekyo sharingan was to kill you best friend he was nearly right. Although I did not fulfill the requirement, the sacrifices I have made to obtain this power are equal, if not greater than slaying my best friend." Naruto looked at Kakashi's face and noticed it sadden to a degree that he had never seen. If he had not known better he would have said that he was about to cry. Kakashi gave a sad smile to Naruto and bid him good night. This left Naruto mentally asking himself what Kakashi could have possibly sacrificed that was more valuable than a best friend. For the second time this night Naruto was snapped out of his thoughts by a voice. "Here is your bill Naruto kun" said Ayame who seemed to wonder if Naruto had learned to sleep with his eyes open. Naruto looked at the bill and noticed that it showed his and Kakashi's meal. The scarecrow had left him to pay for his meal! All the curiosity that Naruto possessed was replaced with disbelief and anger. Naruto seriously considered if his sensei's sadness had just been a ploy to get a free meal.
While Uzamaki Naruto was grumbling at his misfortune the said sensei was at his apartment in a mood one can only describe as depressed. After entering his bedroom Kakashi had only one thought in his head "Was it really worth it?" After losing his father and a large number of his friends, including his best friend, Kakashi was no stranger to losing valuable things in life. It more or less came with the job of being a ninja. However, the one act that gave him the ability to use the mangekyo was the biggest sacrifice of them all. He had sacrificed the one thing that kept him going after seeing numerous amounts of his comrades dying. The one thing that gave him happiness during a nasty bout of depression after Obito died. Under his bed Kakashi pulled out a large oak chest with a teardrop engraved on the top of it. After removing the latches he looked down into the chest and cried. Inside this chest there were ashes, a reminder of the deed that Kakashi had done to gain his bitter sweet ability. The copy ninja's tears began to fall more rapidly and one of the Hidden Leaf's most powerful ninja was having a full fledge sobbing session. The son of the fang of Konoha pushed the chest under his bed and cried himself to sleep. Incinerating his whole collection of limited edition Icha Icha Paradise all signed by their creator and legendary Sannin, Jiraiya with a katon justu had so not been worth the mangekyo sharingan.
