He goes on various B-rank and A-rank missions alongside her which prove especially difficult for him
Isane and Koga travel to Kirigakure to assist some of Koga's old friends with ending some dissappearances.
While in Kirigakure, the the Three-Tails makes a number of random and violent attacks on the islands around Kirigakure.
Isane and Koga's friends attack the Three-Tailed Beast only to fail miserable in subduing the beast
During that battle Koga is knocked unconcious and begins to fight alongside the Three-Tails with great skill and unison in there movements
Isane managages to acquire Koga, however he is left in a coma-like state and afterwards the Three-Tails vanishes
Nearly a weeks passes before Koga awakes from his coma-like state
When he awakes Isane isn't present, inside there cozy shelter. Distraught, Koga decides to tell the Mizukage that the Three-Tailed had attacked
Koga believes himself to have had discussed to the Mizukage, however he was trapped inside a Genjutsu. After breaking the technique he finds himself inside a bunker hidden under a large lake.
Down there he learns of Isane's true intentions, and her reason behind them.
Koga is then told that his friends were killed which sends Koga into a rage, which without his knowing, commands the Three-Tails to being an onslaught on the bunker.
As Koga battles with Isane, above them, an unknown comrade of Isane battles the Three-Tails
Gradually being defeated, Koga decideds to go into a more open space. Thus he unleashes a powerful water ninjutsu which destroys the bunker.
Reaching the top of the water, Koga is introduced to Saimuishin, Isane's husband who would have been the Mizukage had he not been usurped
Working alongside the Three-Tailed Beast, Koga attacks Isane and Saimuishin, however they're unison is more harmful then helpful
Because of there lack of cooperation the Three-Tailed Beast is subdued alongside Koga
Saimuishin reveals his real names as Kurayami
Kurayami attempts to force Koga into a near-death flash which forces the Three-Tails to go rampant which will do what what Kurayami and Isane want, the destruction of Kirigakure
Wanting to alert the Mizukage, Koga attempts to control/harmonize with the Three-Tailed Beast to no avail
However, the intended effect that the near-death situation brings is entirely different as a Kuramoto Clan Seal begins to react
Kurayami then states his distaste for the Kurayami that being the reason why he eradicated them
Koga, angered beyond belief is given newfound chakra reserves with the assistance of the Fuinjutsu and the Three-Tailed Beast, however Isane and Kurayami refuse to give up there goal and continue to pursue Koga
Beyond his breaking point, Koga unleashes a Tailed Beast Ball which nearly kills both Isane and Kurayami
Believing them to be dead, Koga meets with a member of the newfound Seven Swordsman of the Mist which are now a group meant to help Kirigakure grow
Koga is then trained by a member of the Seven Swordsman so that he may understand the Three-Tailed Beast more and deepen his connection with the beast allowing him to be a better Jinchuuriki
Koga beings to ensue a series of missions alongside the Seven Swordsman of the Mist
Koga decides to head back to Konohagakure but rather meet the Mizukage before he leaves
However, Koga much rather impress the Mizukage before he meets him/her for that reason he changes his resolve, a dream to become a powerful Jinchuuriki and stand alongside the Mizukage as an equal
Nearly another year passes before Koga talks with the Mizukage, however before the day begins he meets with Isane and Kurayami who survived the Tailed Beast Ball attack one year ago
Demonstrating his own skill, Koga managed to reach Version 2 of his Jinchuuriki transformation
With his newfound power he defeats both Isane and Kurayami, however instead of killing them he informed them that finding one's own power is more important then stealing someone elses. And that they should lose there hatred, Koga then begins to depart
Isane admits her faults and attempts to persuade Kurayami into giving up all there hate to which Kurayami kills Isane for
Koga then tells Kurayami that he is corrupt and that a child will be the one to depart him on to the next world, he then kills Kurayami
Koga then meets the Mizukage and his new sensei watches on as he is promoted to Jonin, however concealed beneath one of Koga's greatest moments in life, a secretive group arises who wishes to kill him and obtain both his ice ninjutsu and his Tailed Beast