|First Appearance||Vol.1 Chapter 6|
|Last Appearance||Vol.2 Chapter 225|
Hatsu comes from a humble background, from a family with no particular fame. He credits his love for the sword to his father, a potter. Koon calls him a "country bumpkin" and assumes Hatsu is from a more rural area of the Tower, to which he does not deny.
Hatsu appeared on the Second Floor with all the other Regulars. He encountered Anak and began to fight her. Ship Leesoo then turned up, but both Hatsu and Anak completely ignored him. Subsequently, it was announced that the Regulars had to form teams of three, and Hatsu and Anak stopped fighting immediately and teamed up. They continued to ignore Leesoo, but as he grabbed them they ended up on a team with him.
Hatsu then passed the barrier and the Door Test without much trouble owing to Leesoo's high intellect. Ironically, he and Anak were almost disqualified when Leesoo had trouble getting through Lero-Ro's barrier.
He took part in the Crown Game with Anak and Leesoo. He was able to defeat most of the Regulars who attacked him. However, Phonsekal Laure blasted him away with his Shinsoo. After Anak defeated Laure and made a bet with Baam, Hatsu watched the rest of the Crown Game in a moody fashion. At the end, when Anak was about to attack Androssi, he stopped her reminding her of her team. He received an icy response.Scout position for training. During the lessons, he tried to get Koon on his "friends" list. At first, they hated each other, but Baam helped to cool down the tension between them and he became Koon's friend.
He was put on Team B for the Hide-and-Seek test. He travelled with the Spear Bearers on the team, both of whom were very annoyed until Hatsu beat them up. He sensed Quant's ominous presence approaching by using his Shinsoo and told the Spear Bearers to run and throw spears from a distance. Hatsu sensed that Quant was very angry, making the Ranker even more dangerous. He drew his swords and prepared for the coming onslaught. When a Lighthouse revealed Quant, Hatsu blocked his attack and began to fight him. He noticed that while Quant's moves were possible for a regular human, they had been honed to a level that was beyond human capability and into the being that was a Ranker. He decided that he to finish the battle while Quant was still toying with him and leapt into the shadows. He came out at high speed attacking Quant, but the Ranker simply grabbed him in midair and slammed him into the wall. However, Hatsu was able to remain conscious and grabbed Quant's hand, saying that he would not let go, and telling Parakewl and Mauchi to fire, not knowing that they had fled.
In the discussion the Regulars had after Baam revealed himself as an Irregular, he was the first to speak of Baam in a positive manner. When Koon acted like he was abandoning Baam for being an Irregular, Hatsu became enraged and was about to attack him, calling him a coward.
In the Submerged Fish Test, Hatsu plays a minor role of watching the thieves' movements. After the test, he became annoyed with Parakewl who was only concerned about whether they had passed or not since this went against the code of honour he had been raised to. When Parakewl mentioned that Baam was dead and kept using the word dead, Hatsu threatened to kill him. He felt obligated to Baam and influenced everyone to help Rachel climb to the top of the Tower.Part II, recognized throughout The Tower for his skill. He is rumoured to have fought the "Devil of the Right Arm" during the timeskip. Though he was strong, neither of his swords could pierce Beniamino Cassano's arm and the result was a crushing defeat. One of his swords may have shattered, as we only see him carrying one in the second part. Afterwards, he trained relentlessly to strengthen his sword to be able to pierce Cassano's arm.
As The Hand of Arlen was blown up, he along with the rest of his team watched the news grimly, believing the reports of Koon's death. When the invitation to the Workshop Battle was sent to Ship's pocket, he wordlessly followed Leesoo to the next Floor.
When they arrived at the 30th Floor, Leesoo was goggling at the enormity of Archimedes, annoying the highly introverted swordsman. He mock-swung his sword at Leesoo, sobering the atmosphere by reminding them of the mission: to kill Jyu Viole Grace.
He, Leesoo and Anak were running towards the centre of the city where there would be bullets when they ran into Androssi, who had captured Regular paparazzi for their bullets. He lashed out at them when they started randomly supporting FUG instead. After hearing from them about FUG's location, Leesoo deliberately decided that, because of their excess amount of bullets to use to get to Archimedes, to ignore the current game and focus solely on attacking FUG.
Once there, they decide to stay hidden and wait till the tickets given is down to 100. Once the tickets finally reach 100, Hatsu launched an attack on Cassano immediately, although this only served as a warning. With that, the two clash for a few moments. As the two back off from each other, Cassano reminds Hatsu of how the latter was unable to even cut him and his weapon once in their previous battle and that Hatsu lost horribly. But, in response, Hatsu tells Cassano to check his arm if what he says is true. On doing so, Cassano was shocked to see his arm filled with several cuts done in by Hatsu's sword. Thinking Hatsu used some kind of trick, Hatsu explained that the one who trained harder was the one that would win the second clash, describing how he swung his sword billions of times to never lose again. He then thanked Cassano for helping him and his sword grow stronger and proceeded to use Demonic Fish Wheel Dance to inflict deep cuts on Cassano.
After a series of clashes, it is later shown with Cassano done in by Demonic Fish Wheel Dance. But still conscious, Cassano then explained that he was jealous of Hatsu, of how people like him could grow stronger with not just their body, but with the weapon they held themselves. Suddenly, Cassano emerged and clashed heavily with Hatsu. Though Hatsu was able to guard it with his sword, it was revealed that Hatsu's sword had broken in half. Following the catastrophe, Cassano then bid him farewell until they met at the Workshop Battle and a loud bullet shot was heard.
It is later revealed that Hatsu made it, presumably meaning Cassano shot Hatsu with the Holy Bullet to go up to Archimedes. Throughout the day, Hatsu is irritated that his sword had been broken. Later, Leesoo told Hatsu to use Emile to find a shop that sold fresh swords. Though Hatsu was reluctant at first, Leesoo told Hatsu that at times like this, he needed to let his broken sword go and that he needed to move on from it.
Listening to Leesoo, he used Emile for the first time, which lead him to the Acorn Workshop. Confused of the name of the store, he wondered if the place actually sold a "sword that can cut devils". Once at the door, he tried to ring the bell several times, but to no avail. He looked back, and saw Cassano and Horyang approaching the Acorn Workshop as well. Hiding, he witnessed the two enter the door, much to Hatsu's surprise, as he could not do so. Before the door closed, Hatsu goes incognito and gets inside the shop. Quietly following them, he peaked at the room the latter two enter, and witnessed Horyang and Professor Sophia's reunion. Confused about how the two had some kind of connection with a Professor, someone from behind interrupted his eavesdropping.
Hatsu turns around and by instinct "gets his sword ready", only to realize he had no sword. Beta then asked if he was here to "play" with him and if it was fun to eavesdrop. At that moment, clear increments of Shinsoo sparks began to arise from Beta's body. Right after, Cassano and Horyang left the room and caught Hatsu red-handed. Hatsu, realizing his situation, was later seen with his wrists tied and thrown into a room. He demanded that Cassano let him go and questioned on what was happening. Cassano only responded by saying that they would lock him up only till after the Workshop Battle. He then locked him in the room.
He untied the ropes, remarking how bad Cassano was at tying others up is. Left with no other choice than to rely on Emile once again, he asked about a way to escape from the cell with her advising him to look under the bed, where a hidden passage was located. Hatsu realised that the passage lead to a wide area due to the flow of Shinsoo and wondered where Emile might be sending him.
Hatsu continued with his escape plan. He ended up in a wide area where he encountered a door. As he was approaching it, a Workshop Patrol appeared and attacked him. After a short struggle the determined Hatsu managed to paralyse it by using a steel pipe reinforced with Shinsoo, which initiates the self-destruct sequence. In the end he was saved by Lero-Ro who destroyed the patrol with a single strike. Lero-Ro then asked for Hatsu's help, telling him that they were going to prevent the creation of the most terrible weapon.
From the bushes, Hatsu appeared, calling out to Leesoo. He frantically told Leesoo that they needed to stop the creation of the most terrible weapon because Baam was in danger.
When Leesoo encountered Koon, Hatsu appeared behind Koon with a gun pointed at his back and told him that they knew everything. Koon wondered how they knew Baam is alive, with Hatsu revealing that it was Lero-Ro that gave him the information as well as being on Archimedes. Koon was surprised to hear that Lero-Ro was on the ship. Hatsu then explained why Lero-Ro was on the Archimedes and what he had discovered as a result of his investigation, much to Koon's horror.
Hatsu told the others the same things he told Koon, shocking them all at the news. Rak frustratedly demanded to know why Hatsu withheld such information if he knew; Hatsu merely replied that he couldn't do anything at the time. This was actually due to FUG monitoring all of Baam's friends closely.
With the information Lero-Ro told Hatsu, he was able to help Koon finalise the details of his plan to summon Viole. Later on in the tournament, as the team prepared to carry out Koon's plan, Hatsu was seen sharing the tournament-given Lighthouse with Leesoo.
When Beta first appeared, Hatsu recognised him as the one who led Viole into a trap.
When the Workshop guards attempted to eliminate Beta, Hatsu helped out in subduing them. He then stood with everyone present as Koon, Rak and Baam were reunited, with Leesoo noting that the strongest team was back.
When the group splits up to retrieve the three hostages, Hatsu teleported with Androssi to Varagarv and Ron Mei's location. Hatsu reminded her that they only need to stall for time and then called out in worry as she launched herself at Ron Mei. After witnessing Varagarv damage Androssi, Hatsu used Bong Bong to teleport her out of danger. He then reasons that Varagarv may well be the most difficult opponent Androssi faced. After Hatsu took everything into consideration, he told Androssi that they would be attacking instead and he would cover her using his new sword, a metal pipe. The two launched themselves into attack with Hatsu dissipating Varagarv's Shadow Wolves, enabling Androssi to teleport both herself and the Mad Dog high into the sky. After she brough Varagarv crashing down, he forced them to concede defeat after holding Ron Mei hostage.
He travelled with Androssi as she teleported around moving the hostages to safety and then boarded the Wolhaiksong escape ship with everyone else.
He says his goodbyes to Baam as he leaves with the rest of his team to begin climbing the Tower again.
He was very briefly seen, alongside the rest of his team, training with strapped to his back and standing in a sword-wielding position.