Hokkai was born in Kirigakure following the events of the fourth shinobi world war, he was born to a fugitive of the nation, and a well known Hōzuki man. His mother was wanted for her Kaguya heritage, although she was able to blend in for quite some time and having avoided capture for years she met his father, who had no idea she was wanted for simply being a member of her clan.
Hokkai was a rather cheerful child who much enjoyed the company of his mother, and enjoyed any amount of time he could spend learning new things with her, due to her heritage her living in the village was out of the question forcing Hokkai to ignore his Hōzuki blood for almost a decade. After his training began with Suigetsu, Hokkai's sunny disposition faded, in place of a deep rooted thirst for knowledge of things he missed in his early childhood, this was evidenced when he thanked Suigetsu for his training despite the harshness of it. Following Suigetsu's training Hokkai had grown into a passionate individual that held a distaste for the hierarchy of Kirigakure, having shunned and oppressed his entire maternal clan for decades, despite their own wrong doing. This drove him to defect the village taking everything he had learned, and everything he had earned. He decided to find a place to call his own, and to embrace both sides of his heritage.
Hokkai was a very capable student his will to learn allowed him to soak in even the smallest details of an attack, perfectly replicating it when given some time, this was proven during his test with Chojuro, having only saw Chojuro use the Hiramekarei for a few moments, Hokkai had learned to use it in a similar manner from simple observation. His Kaguya genes also granted him the ability to manipulate the flow of calcium with his chakra giving him the ability to protrude sharpened bones from any point on his body, he also showed the ability to use the Hōzuki clan hiden: the hydrification jutsu, allowing him various forms. His skill with the jutsu allowed him to replenish himself with the water molecules present in the air. Hokkai's calcium-based liquid can dissolve any sort of organic cells, including plant, bone, or even fertile dirt and dissolve them, destroying them at a cellular or even protein level, allowing him to destroy his targets, either by a specific part or outright disintegration. He can also dissolve viral or germ-like cells from his own body for self-treatment. Hokkai can even overpower all forms of cellular regeneration by disintegrating cells continuously, overwhelming and negating the healing process until there is nothing to regenerate from.
Hokkai being a Hōzuki clan member gave him a natural affinity for the Water Release nature, he was also very capable with Wind Release, enhancing his water jutsu with the destructive force of the wind release. As well as Using Wind Release with the Shikotsumyaku,for enhanced physical attacks. When wielding the Kiba, his lightning release was greatly inhanced as well.
Being a Kaguya clan member by blood, and having his great cousin Kimimaro's techniques taught to him, boosted Hokkai's taijutsu skill to master levels, he was also seemingly experienced with street fighting styles such as Boxing, and Kick-Boxing.
He was taught to wield swords by Suigetsu at the request of Chojuro, who had given him his own Hiramekarei, Hokkai's natural learning ability allowed him to wield the entirety of the Ninja Swords during battle even the notoriously picky Samehada, following his defection he continued to practice with the blades, eventually creating a summoning mechanism that was strapped to his arm hidden beneath his sleeves that held the scroll, and with different handseals, will allow to him to summon the blade assigned to each seal allowing him to switch the weapons with ease.
Rumors of a hybrid child spread throughout Kirigakure, and harboring fugitives of the nation was not taken lightly to. The Current acting Mizukage Chojuro, had investigated the home they had supposedly been staying only to find that it had been empty, and appeared that it was that way for some time now. Hours prior to this, Hokkai's mother had fled from the home not even saying good bye to her husband who wasn't around on that day, she used her Shikotsumyaku to destroy the insides of the home and alter its appearance, like no one was ever there. Following this she gave birth to a newborn son, who she could almost sense a destiny rising for. She named him after his father to prevent any suspicion of his heritage and then raised a young Hokkai teaching him the most basic of his maternal clan's techniques. Around his tenth birthday she sent him to Kirigakure for testing which he managed to pass although his skills weren't top notch he was able to produce water and create a successful clone of himself. Eventually becoming a genin, he returned to his mother who had surprisingly had a strange man in the house with her. She explained to Hokkai that this was his Hōzuki father, and he had come to take the boy deep into Kirigakure to learn of his heritage. After a teary good bye from his mother he and his father headed to the Hōzuki compound to meet with none other than the current clan head, an elderly Suigetsu Hōzuki. Suigetsu saw much promise in this child, extending a hand in his training. Despite his near crippling age Suigetsu's water filled genetic make-up was keeping him spry and full of energy. After a few years of training Hokkai was capable of using much more advanced Water Release jutsu. On a fateful day in his 14 year of life, his father returned to the compound carrying a rather unique scroll, Suigetsu immediately recognized this scroll extending his hand to Hokkai's Father, upon opening the scroll his suspicions were confirmed it was his brother's scroll.
A Test of Valor!
Hokkai's continued training with Suigetsu proved to make him extremely capable in just a few short months. He was able to handle multiple shadow clones of Suigetsu, giving him at least enough skill to handle a small group of opponents. When Suigetsu saw this growth he decided it was time for Hokkai to learn his limits. He removed the scroll and unraveled it showing it to Hokkai, soon a plume of smoke erupted from it as two swords appeared it was none other than the Kiba, both of which Suigetsu gripped and charged at Hokkai, when Suigetsu went to slice at Hokkai, the latter used the hydrification technique attempting to avoid the damage, the blade soared right through Hokkai, about halfway, it was then Hokkai felt a pain unlike any other, Suigetsu used the lightning embued in the sword to shock Hokkai, not with enough voltage to kill him, but with enough to knock him out, Hokkai's passive Kaguya genes then activated as bones formed within the water of his body, gripping the Kiba, forcing Suigetsu to release it. Suigetsu had saw this before, in his time with Orochimaru. He decided to not tell the Mizukage and keep this secret to himself, removing the blade using its enhanced cutting ability he knew with regenerative ability of a Kaguya the boy would be fine. Suigetsu headed to Hokkai's Father to question the where abouts of his mother. During his stay in the Hospital, he saw the former Mizukage Mei Terumī who commented on his looks, and Hibiki Ryūsei whom he made an instant connection with.
Return of the Shikotsumyaku!!
After grilling Hokkai's father while the boy laid in recovery, Suigetsu found out his mothers whereabouts. He used the Mist Body Flicker to appear in the Land of Sound, he began to rummage through the base Orochimaru kept his recordings of his experiments in, Following the injection of his Sage Chakra into the sound 5 Orochimaru began to record the way in which they each used Jutsu, he removed Kimimaro's scroll and began to read it, seeing the details of Kimimaro's basic jutsu prior to his sage chakra injection. He activated the Mist Body Flicker again, this time appearing within the area Hokkai's mother resided in. He found her finally she turned him away recognizing him as a clan head of Kirigakure, her instinct kicked in and she fled. Suigetsu followed her to tell her about how he knows she was a Kaguya clan member. This same news to her was deathly as she continued her sprint. Suigetsu finally caught up to her explaining that her secret was safe, he further explaines her sons current situation and that her advice in his training would be instrumental. He gave her the scroll of jutsu which she read and then demonstrated them all within mere hours and Suigetsu left to check Hokkai's recovery rate, the boy had made a quick recovery and could continue his training. Suigetsu along with Hokkai returned the next day. His training with his mother had greatly improved his control of the Shikotsumyaku, he was capable of creating fields of bones, or even armor. He and Suigetsu rerurned to Kirigakure in another year, he was considered for promotion to Chunin by Suigetsu for having mastered his own bloodline at such a young age.
Seven Ninja Swords Reassemble
Upon hearing Suigetsu's Request, Chojuro himself decided to test Hokkai. After a training session in which Hokkai learned to increase his muscle mass with water. Suigetsu gave news of the Mizukage's special Chunin exam, Hokkai was instructed to the Mizukage's mansion. Around that time Suigetsu heard of the 8 tails host, dying and the beast being released left to guard Kumogakure, without a jinchuriki. This reminded Suigetsu of the Samehada, a sword he once sought after. The Hōzuki clan head removed the scroll of the seven ninja swords, summoning Samehada. The sword appeared in its fully bandaged form, wrapping it's hilt around Suigetsu's arm to test his chakra. It seemed indifferent but nonetheless accepted the loss of it's previous wielder. In the mean time during his training with Chojuro, Hokkai experienced the power of the famed twinsword firsthand having to rely on the hydrification jutsu more than he originally intended to, to null the physical striked of the mizukage, and to avoid some chakra based attacks altogether. He then pointed his fingers toward Chojuro releasing the strongest water bullet he could, it raced toward the Hiramekarei which knocked it out of Chojuro's hand giving Hokkai the time to grab it and turn it against it's wielder. Chojuro was impressed by the fact that Hokkai could use the hiramekarei with such ease for the first time, however the youths lack of swordsmanship skills were still quite obvious, his stance being one of many things done wrong. Chojuro had decided to pass Hokkai on to chunin, as well as gift him the Hiramekarei, stating that Suigetsu will be instucted to teach him the way of the sword. After he finished speaking with Chojuro, Hokkai saw the girl Hibiki and began to explain his acquisition of the twin seord, she expressed her desire to become a swordsman of the mist, something Hokkai shared. After spending sometime together with her talking about the future, Hokkai returned to the Hōzuki compound with the bandaged Hiramekarei hanging on his back.
His continued training with the Hiramekarei, improved his kenjutsu skill greatly, allowing to easily dispose of a group of jonin-level ninja, he also became even more potent with the unleashing of the blade, prompting Suigetsu to teach him to wield all of the blades, as well as create a large avatar made of water. Chojuro learned of his progress and decided to reinstate the mist swordsmen. Suigetsu helped the rapidly growing child to become a master of the Silent Killing, as well as cloak a field in mist. When he returned to his mother he found that she has disappeared, and told his mentor Suigetsu, he wanted to search the world to find her no matter how long it took, only for Suigetsu to deny his request stating that with his new position, finding more members was more important than familial ties. Hokkai wouldn't accept this, and defected from Kirigakure, after taking the scroll in the dead of night, before he left he headed to Hibiki's home with Mei, he tapped on her window before explaining he was about to defect. She expressed her desire for him to stay but also told him to "follow his heart", he left her a scroll containing half of the swords from the scroll. The next day his travels through the land of water lead him toward the previous Kaguya Clan compound that since the massacre had been destroyed prior to the massacre long ago, as if almost genetically, his memories accessed a hidden area it was like he was having a flash back to a time when his mother was still young, the thoughts of his clan while they were facing oppression turned Hokkai's previous passion for kirigakure, made way for a deep feeling of hate to root in his heart, despite the fact that Chojuro had done nothing but help the young Hōzuki, Hokkai still felt a great distaste for the heads of kiri, the mizukage included. Hokkai could hear the footsteps of an approaching group, "Hunter-nin?" He questioned as he prepared to set a trap, to make sure that Kiri understood he was not interested in returning, at least not now. He performed the Kirigakure no jutsu, blanketing the area in a thick mist, his training with suigetsu paid off, as when the group approached they were unaware he was even in the vicinity. Hokkai heard them mumbling "the tracks have stopped he must be he-" his words were cut short as Hokkai performed the mist body flicker, and impaled the kiba into the man, followed by a wave of electrical chakra that soared to his comrades killing then all in a single swift motion. He continued on his path to find his mother with a new goal as well, to find a place to continue the Kaguya clan safely.