Homura and Koharu, the village elders voted for Erza to be the nest hokage however, she went back to Fiore so the two elder agreed with Suna's recommendation that Kakashi become their next Hokage. Kakashi wanders around Konoha thinking about his future as Hokage and looks at Minato's face on the monument. Just then, Might Guy appears and challenges him to race. Kakashi ultimately wins the race, albeit very closely, and Guy congratulates him on becoming Hokage, claiming that from now on Kakashi would be too busy for their challenges. However, Kakashi tells him that they will always be "eternal rivals" and that he is happy he is there and would need Guy's help running the village, leaving Guy in tears.
Later, the members of the Land of Fire, including the Fire Daimyō, as well as the Konoha Council, hold a meeting to officially appoint Kakashi as the next Hokage. The daimyō is unsure about whether to appoint Kakashi as the sixth or the seventh Hokage, as he had appointed Danzō as the sixth earlier, although Danzō did not formally take office. Koharu protests that Danzō should still be recognised as the sixth, while Homura shakes his head. In the end, the daimyō makes his decision that Kakashi Hatake now is the 6th Hokage of the Hidden Leaf Village.
"I remember Erza promised to return to Konoha to stay by my side when I become the hokage. I wonder how's she doing right now? I miss that woman" Kakashi said with a sigh as he looks at the sky
Meanwhile in Fiore, Natsu and Elfman start a fight which the rest of the guild soon enough joins in. Levy is stuck on the paperwork of the guild, stating that they ought to choose a seventh Guildmaster, one who could maintain the vulgar members. Her question is then answered shortly when an irked Erza scolds the brawling Mages to get back to their work, freezing all of them on the spot.
Baffled by the sudden decision, and the immediate approval of the guild-members, Erza stutters, but is interrupted by a young man, who is actually Mest Gryder, quickly accompanies Erza into the underground area of the guild and introduces her to Lumen Histoire. While explaining that only Guild masters are allowed in there. Surprised to see Mavis's body engulfed in a great crystal, Erza asks Mest for explanations, prompting the latter to state that he also hosts little information about it. Levy finally filed the guild's paperwork declaring Erza Uchiha as the 7th guild master of fairy tail.
"I never have thought to be the master of the guild. I wonder if Kakashi finally became the hokage, he deserves it and is very capable of having that position" she said inwardly, the thoughts of kakashi made her blush as she smiles to herself.
Two months later in Konohagakure, Naruto, having recently acquired a prosthetic arm to replace the one he lost during the War, tries to get Kakashi Hatake's attention. After failing to ignore Naruto, Kakashi allows Naruto to ask him the same question everyone else does: when will he officially take on the responsibilities of Hokage. Naruto points out that Kakashi's face has already been added to the Hokage Rock, so for Tsunade to continue to be in charge confuses everyone. Naruto also argues that Tsunade is too old to continue being Hokage and unfit for the responsibilities, unaware that Tsunade is behind him.
After Tsunade angrily knocks Naruto unconscious, she too asks about Kakashi's plans. He asks for her to wait until his current mission is complete before demanding his decision. Kakashi is to oversee security for the maiden voyage of the Tobishachimaru, as most of Konoha's other forces are on guard duty for the Blood Prison in the wake of the death of Mui, its previous warden, several years earlier. Tsunade wishes Kakashi luck and reminds him that the Tobishachimaru's existence is currently supposed to be a secret from the other Five Great Shinobi Countries and that she have sent Erza a letter telling her to come home since Kakashi is now rokudaime.
He remembered that Erza told her a way on how they can communicate between worlds. She told him about the Miniature Communication Lacrima A rectangular-shaped device, resembling a mobile phone, allowing long-distance calls, although depending on the distance the connection could become weaker, thus making it harder to understand or decipher what the other side is saying.Luckily Erza is so skilled in magic and chakra control that it will work even if the other is on other dimension. This particular Lacrima was invented by Warren Rocko of Fairy Tail.
Makarov Dreyar, the former guild master left because he is afraid the might of the western continent threatening to launch a full-scale war against Ishgar to claim Lumen Historie is impossible to ignore. Makarov explained how now with the combined might of the Alvarez Empire, now being too much to overcome with the destruction of Etherion and Face, Ishgar is more vulnerable than ever; to which he declares he will journey to Alvarez to negotiate and buy time from the inevitable war. However, within the past year, there has been no contact with Makarov to which Mest speculates that he has been either taken prisoner or in worst case scenario, even death. This prompts Mest to inform the 7th guild master, Erza, who recruits the other members of Team Natsu to go on a secret mission to Alvarez to retrieve their master.
Before Erza leaves for her mission, she decided to call Kakashi with her lacrima.
"Hokage's office" Shizune answered the call
"This is Erza, may I speak with Kakashi?" She asked
"Oh it's you lady Erza, I'll call the rokudaime for you" she said
"rokudaime? he made it then" she said inwardly. Kakashi ran towards the phone in excitement
"Erza! I'm glad you called. I was thinking about you and wanted to call you but I don't know how" he stated
"Of course I'll call, I miss you fool. I got Tsunade's letter. Congratulations! I never had a doubt"
"I miss you too, thank you, so dies this mean you'll stay with me now?"
"oh about that... that's why I called... Can you wait for me a little longer?"
"What happened? is everything okay?"
"uhm, yeah, it's just that I never expected to be the 7th guild master. Makarov is missing, so team Natsu- we'll go on a mission to rescue him and I'll resign once his back here safe, then I'll be there"
"Congratulations! Be careful Erza, I don't want you hurt nor dying, you hear me woman?"
"Yes Hokage sama" she chuckled which made Kakashi laugh
"I'll go on my last mission too before officially taking on being a hokage"
"Good luck kakashi and go home in one piece or I'll make sure you suffer pain worst than death"
"Yes master, damn I so love you Erza"
"I love you too" and she ended the call.
Kakashi and Guy infiltrate the ventilation ducts so they can move around the ship and gather information unnoticed. They watch as the ship's passengers are gathered into the dining area by enemy ninja and their leader, Rahyō. The Konoha ninja that have been inserted onto the ship as security engage the opposing forces, but their bodies are frozen from some remote location by a person named Kahyō. Rahyō tells the passengers that they are being taken hostage until Garyō is released from the Blood Prison. Starting in half an hour, if Garyō isn't freed, one hostage will be killed followed by another every subsequent ten minutes. Additionally, if Konoha involves Naruto Uzumaki in this, the Tobishachimaru will be blown up.
Kakashi summons his eight ninken and sends them to find all the explosive tags planted around the ship. As the ninken disperse, Kakashi finds a safe place for the woman to hide. Because time is running out, the woman pleads with him to release Garyō so that nobody will be hurt. Kakashi responds that he can't do that, but promises that he will save as many people as he can. Kakashi attacks members of the Armament Alliance and neutralises several, to which Rahyō responds by freezing two hostages to death. Rahyō offers to give ten more minutes for Konoha to comply with his demands before killing anyone else if Kakashi surrenders. He does so and is bound with ropes.
Kahyō becomes angry by Kakashi's observation and performs another Earthen Consecutive Chains of Ice that starts spreading across the area, engulfing everything it comes into contact with. Rahyō tells Kahyō to stop and, when his order is ignored, he knocks Kahyō unconscious. Though the Chains of Ice disappear, a hole is left in the floor and the different pressures between inside and outside start sucking out passengers. Kakashi catches Guy before he's sucked out too, but cannot maintain his grip on the ship's hull. Guy tells Kakashi to save himself and Ino breaks in asking for an update, but Kakashi can only focus on one thing: Kahyō's mask has come off, revealing the woman he met earlier. Kakashi loses his grip and starts falling.
Kakashi watches around him as he falls through the air with many other passengers. He makes eye contact with Guy and together they accept the fact that they're about to die. Just as Kakashi starts to reflect on what death means for him not seeing Erza again, he and everyone else are saved by Sai. Kakashi informs Sai of what they learned about the Armament Alliance's shinobi and asks how things are going on Konoha's end. It becomes apparent that events are not going in the Armament Alliance's favour, which Kakashi assumes they will have prepared for. Kakashi sends a message to Ino that Tobishachimaru is heading to Blood Prison and asks Sai to take him back to the ship so he can try and stop it. Sai complies, but finds the Tobishachimaru has risen well above its usual altitude owing to the ongoing conflict on board.
Because of how many passengers died because of the Armament Alliance, Kahyō should be sentenced to death. However, Kakashi is willing to reduce her sentence to life-imprisonment if she will agree to be the new warden of the Blood Prison, dedicating the rest of her life to keeping those imprisoned there within its walls. He explains to Tsunade how the Chains of Ice work, and how they make Kahyō uniquely qualified to replace Mui, the previous warden. Shikamaru approves of this, believing it will be in all the villages' best interests. Tsunade agrees on the condition that it be Kakashi's first act as Hokage. Kahyō vows to accept this assignment if that is what Kakashi asks of her, so he officially takes on the title of Sixth Hokage.
Team Natsu alongside with Mest depart on a ship towards Caracole Island, in order to rendezvous with their contact that holds valuable intelligence concerning Makarov's location. As the Fairy Tail Mages approach the island, they notice Alvarez Navy ships moored at the bay and realize they have to use stealth in order to hide their allegiance. They present themselves as Cait Shelter Mages while being subjected to routine check by the marines and are allowed to enter. While there, they notice a child desperately looking for his father, which annoys an imperial marine, who promptly attacks him with a knife. Seeing this, Team Natsu rushes in to defend the child and defeat the marines.Having successfully rescued Makarov and returned to the rebuilt guild, the Mages of Fairy Tail joyously celebrate by throwing a party. Erza resigned as the guild master giving the position back to Makarov and asked his permission to leave the guild and go back to konoha which he granted.