- "You are weak."
- — Haseo —
Unlike other PCs, Haseo has an entirely different color scheme and outfit than his normal form for his Xth Form. The black shirt with matching detached sleeves that previously exposed his stomach is now replaced by a sleeveless white shirt with a black and orange mantle adorning his back. Light red plasma-like appendages are also attached to the mantle. His black cargo pants and shoes are swapped out by white, partially-armored ones. Red circlets are placed near his biceps and his gauntlets. Haseo's hair is more subdued in his Xth Form, and his tattoo designs are changed. Unlike other PCs, where they have subtle changes to their signature weapon, Haseo's knives are changed into guns with orange plasma-like blades attached.
Haseo normally comes off as a somewhat rude person that approaches teamwork with his teeth clenched. While he does have friends that he deeply cares about, it takes a while for those new to him to see such hidden depths. Signs of affection and gratitude are relatively rare to him, and due to this, he becomes a little embarrassed when treated with such, as shown in his initial Cross Rengeki with Tokio, where he blushes and looks away.
Haseo first appeares in 2016 during Tokio's introduction to the Twilight Brigade members, and Ovan instructed him to clear an area mission with him. After Ovan's disappearance, Tokio was about to stop Shino from going to the Hulle Granz Cathedral alone, but was stopped by Orgel. Tokio was left with no choice but to tell Tabby to send message to Haseo to go to the cathedral as fast as possible, only to arrive late and witness Shino being PKed and turning into a Lost One. Afterwards, he sent Tabby and Tokio messages to meet him in the Twilight Brigade's @home. When Tokio and Tabby arrived, Haseo questioned Tokio about how he knew that Shino would be PK'd in the Cathedral. Haseo then started to blamed Tokio for what happened. Tabby stepped in and defended Tokio, but the anger-filled Haseo wouldn't listen to a word she said, and in a fit of rage, he left the Twilight Brigade.
In 2017 Tokio met Haseo again while the latter was fighting Bordeaux and her minions Negimaru and Grein. Though the trio were intimidating, Haseo defeated all three of them in an instant. He recognized Tokio, but he stormed off, but not before harshly saying that after a long time, there wasn't any need for Tokio to return to The World. Later Tokio followed him with Atoli after Saika located his whereabouts. Haseo was trying to summon his Avatar, but he was unable to call upon it. Then Tokio and Atoli arrived, offering to help him save Shino, but Haseo refused, as he still blames Tokio for everything. Shortly afterwords, Atoli heard AIDA's sound and fell to the ground, unconscious. An AIDA appeared and attacked, so Haseo went to her defense and to his surprise, he successfully summoned Skeith and defeated the AIDA. After the battle, he left the area.
Since the Chrono Core was inside Haseo this time, Saika once again tracked Haseo and found him in the area where Shino became a Lost One. Tokio went to the Hulle Granz Cathedral and once again, Haseo gave him the cold shoulder. Tokio tried to explain to Haseo what happened, but they were interrupted by Azure Kite's arrival. Haseo recognizes the azure knight as the one who was in the cathedral during Shino's PKing, and so, he briefly fights him, but to his surprise, none of his attacks would work, and he was swiftly defeated by Azure Kite.
Sometime after Haseo reappeared with Atoli, who invited both him, and Tokio, in a party. She believed that they were now close friends ever since they all first got together. But Haseo, enraged by Atoli's naivety, shouted at her, telling her to never show her face in The World again.
A few days later, Haseo decided to enter a tournament inside the Arena, where he easily defeated Alkaid, and later, Endrance, using his berserk Avatar, Skeith. Kuhn confronted him with anger, due to Haseo's irresponsible action as an Epitaph User. Haseo sneered and said that Kuhn was too soft, and defeated him with his Avatar. At this time, AIKA sensed an AIDA within Haseo, realizing that Haseo was attracted (and controlled) by the AIDA, due to his lust of power and his hatred for Azure Kite, who he believes to be Tri-Edge, the identity of the one who PKed Shino.
One day, the Moon Tree @home was invaded by a massive amount of AIDA. As he and Tokio cleared the way, Haseo confronted Atoli, who was also infected by AIDA. Haseo then defeated Atoli's Avatar, Innis with Skeith, thus freeing Atoli form AIDA's control. He was about to deal a finishing blow to Atoli, but then, he remembered Shino during the moment she went into a coma, and Atoli's words at the last area they went in together, this made him him hesitate at the last minute. Tokio stepped in while Haseo was hesitating, but to Tokio's dismay, the Terror of Death turned his annoyance towards Tokio and attacked. Fortunately, Tokio was able to make him realize that the reason he came to Moon Tree is not to defeat Atoli, but to save her. This gave AIKA the opportunity to calm the AIDA within Haseo.
Afterward, Haseo sent Atoli a message, telling her to come with Tokio to the Hulle Granz Cathedral. There, he apologized to Tokio, and the two reconciled, restoring the friendship they once had. Later at the PK Tournament Sakaki, Haseo invited Tokio to enter the tournament to defeat Sakaki with him, and free the arena from the AIDA's influence. After they defeated Sakaki, Haseo saw Ovan, who had been watching him from the beginning as he left. Soon after Ovan sent Haseo and Tokio messages to meet him at the Creator's Room. There, Ovan revealed to Haseo that he was in fact, the true Tri-Edge, the one who PKed Shino. Knowing this, Haseo fought Ovan with his Avatar against his, which resulted in Haseo being victorious. A weakened Ovan then revealed his true plan, to activate Corbenik's Rebirth power in order to save his sister, Aina. As Ovan activated the Rebirth power, Haseo disappeared along with him, leaving a dumbstruck Tokio alone.
Later when Tokio went to the cathedral, as Saika detected a Chrono Core there. When he arrived, Tokio heard Haseo's voice, apologizing to him as Haseo's Chrono Core appeared in front of Tokio.He reappeared again after several days, reluctantly helping Gaspard's guild shop, much to Tokio and Atoli's surprise (since Haseo's attitude, while running the shop, was complete opposite of his usual self). Both of them followed Haseo everywhere until they came to the Hulle Granz Cathedral, where Shino regained consciousness, and was waiting for Haseo to arrive. When he came, Shino offered Haseo a chance for them to restart the Twilight Brigade with just the two of them. Haseo however, declined this offer.Outside the Cathedral, as he was about to head back to town, Haseo met with Atoli (who he didn't realize was actually eavesdropping with Tokio inside the cathedral). Atoli thought up some excuses, but she was interrupted when a blushing Haseo suddenly asked for her to come with him. Both the Terror of Death and Atoli became embarrassed, but Atoli smiled and agreed to go with him, so they left the area together.After this, Haseo's PC in 2020 was revived, and he joined the Twilight Knights with Tokio and the other new members, preparing for the final battle with a virus-infected Aura.
Haseo appears at first as an antagonist before Tokio could befriend him. Haseo attacks a large group of players with the same blood lust during his days as the PKK The Terror of Death. After Schicksal alters the data in the Akashic Records under CC Corp, Haseo's memories were affected. Posaune shows his own interest and by having Haseo come in contact with Tokio at Lumina Cross. Haseo is shown a false vision and the misinterpretation causes him to burn a hatred for him and think Tokio is the one who PKed Shino.
Afterward Posaune remodels and reinforces Haseo, reaching level 200 which is outside of the specifications of The World. His right arm is also installed with a sharp claw with two systems. Haseo later challenges Alkaid to reign as arena champion. He defeats and overturns her with power and pins her to the floor. Already in the worst situation Saika interrupts the match, but it is impossible for her to capture the Chrono Core. Furthermore Alkaid is manipulated by Posaune who then remodeled and reinforced her.
While wandering in a small town, Haseo found Tsukasa and attacked him because of his connection to Tokio. He demanded the location of Tokio, but Tsukasa refused to tell him, prompting Haseo into attacking the wavemaster. But suddenly, Azure Kite interfered and battled Haseo, giving Tsukasa the opportunity to escape. During the fight, Posaune captures Azure Kite and throws him into a cell, where he tries to brainwash Azure Kite the same way he did to Haseo and Alkaid. Later, Haseo approached the azure knight, wondering if he has met him before...
He encountered Tokio and Tsukasa in the Arena with Posaune and turned into his Beast Form and heavily injured Tsukasa, giving Posaune the opportunity to steal Tsukasa's Chrono Core. However, Tokio was somehow able to free Haseo from Posaune's control, and together, they defeated Posaune. Later that day, Haseo encountered Azure Kite, and the two decided to join forces.
- Haseo is the only UPC that is able to freely switch between his 1st and Xth form.
- Haseo is also the only PC that already had an Xth form before R:X.
- Haseo's Xth Form is almost identical to his appearance in R:2, though with the addition of two of the seven beam wings he demonstrated in the Trilogy movie.
- Like Kite, Haseo's Xth Form changes him from a physical fighter to a ranged one.
- Haseo's Xth Form was later featured as a dlc costume in Tales of Graces ƒ for Asbel Lhant similarly Haseo can unlock his costume in .hack//Link.
- Like Kite and Tokio, Haseo's Xth form has the most dramatic change in appearance out of all the Xth Forms.
- Haseo uses his scythe, but only as a boss.