Personality & Character
Sekai's personality is similar to that of Domon Kasshu's, like Domon, Sekai uses a close combat oriented Gunpla, utilizing his martial arts skills.
It appears that Sekai doesn't know that much about social activities, such as when he told his sister that he was going out on a date. He then asks her questions about dates, such as what to wear. He does however manage to figure out that Yuuma only spent time with them so he could be with his sister Mirai, and blushed when kids wanted him and Fumina to kiss. He is a very straightforward person which is noticed by many people who approach him. This aspect of his personality is both a asset and a weakness when it comes to Gunpla battle which is shown through his battles with Shimon Izuna and Team SRSC.
Unlike both his teammates, who are often concerned with winning, he only enjoyed fighting battles for enjoyment, and only gets excited about fighting someone strong and never for once shows any worries about the possibility of losing before battles.
Being considered as the "Second coming of Reiji" due to his natural flair for Gunpla battle, Sekai also bears a strong resemblance to Reiji in both appearance and personalities. Like Reiji, Sekai initially has no knowledge about Gunpla or Gunpla Battle and was only interested in Gunpla because he found a outlet to use his martial arts skills to the fullest and it is fun fighting battles, he begins to learn more about Gunpla throughout his fights and comes to gradually fall in love with Gunpla in general along the way, eventually vowing to dedicate himself to learn more about Gunpla and grow as both a builder and a fighter. Similar to how Reiji did not notice Aila's romantic feelings for him, Sekai is also dense in the this area as even though Fumina, Kaoruko, and Shia are fighting for his affection right in front of him, he still has no clue about it.
As a martial art practitioner, Sekai has high tolerance to pain and can withstand crippling damage from assimilation.
After being arrested for scaring a gang in a back alley with his martial arts skills, Sekai Kamiki arrives at Seiho Academy as a second-year transfer student. As the last remaining member of the Gunpla Battle Club struggling to form a team to participate in the upcoming Gunpla Battle Tournament, Fumina Hoshino convinces Sekai to join her club. Sekai is transferred to the same class as Yuuma. Meanwhile, Sekai and Fumina must battle Miyaga, Yuuma, and Eri alongside Hoshino in a two-on-three battle to prevent the Gunpla Battle Club from being absorbed into the Plamo Club. Following his humiliating defeat at the hands of Minato Sakai, Sekai struggles to adapt his Jigen Haoh School techniques in different environments while Yuuma upgrades his Lightning Gundam. Meanwhile, Fumina reveals her inspiration for taking up Gunpla Battle as a hobby, and she completes her latest Gunpla just in time for the qualifying tournament.
On the day of the Tournament Sekai is escorted by Gyanko as he had no clue where he was going. After a brief argument between Gyanko and Fumina, they entered the arena and faced their first opponent. Yuuma and Fumina defeated their targets in no time and then Yuuma told Sekai to let him handle the remaining one but Sekai told him he could do it and he proceeded to run through space, and defeated the last Gunpla with his Jigen Haoh School techniques, winning his team the match. After a brief scolding from Yuuma, they are hugged by Fumina. The next day they were placed against the Genius team who always changed their Gunpla so no one could predict their strategy but luckily Fumina had a trump card that she had showed Sekai and Yuuma before the match; the "Winning Road". During the battle they couldn't communicate due to jamming particles which caused Sekai and Yuuma to keep colliding with each other. Fumina then separated her Winning Gundam into weapons for Sekai and Yuuma, who then proceeded to easily overpower their opponents. They managed to disperse the jamming field using Sekai's martial arts while equipped with the "Winning Knuckle".
They were pitted against Team Angel Fish who were a very favored team but they defeated them easily as Team Angel Fish couldn't use water as they were in an Ice Field giving team Try Fighters an easy win but disappointed Sekai due to the battle being one-sided. Their next opponent was Team F.A.I.T.H. and they were begged by two members of the team to let them win as Simon’s brother was ill and they needed to win for him, to deliver the trophy. Sekai declined and left to go see Mamoru who he showed his Gunpla and let him play with it for a while until Simon arrived and Sekai told him they won't let them win and they will fight him to the best of their ability. The next day they battled Team F.A.I.T.H. and Sekai was shocked to see Simon's teammates go and fly right into Yuuma and Fumina and force them out of the field leaving only Sekai and Simon to battle one on one. The following fight as intense, but Sekai managed to muster what was left of his strength and win the match with his badly damaged Build Burning Gundam.
The next day they were placed against a giant Mobile Armor, but they worked together and defeated it. After the battle Sekai was confronted bye a crying Gyanko who hugged him and told him she doesn't think she can win against team Miyazato High School so Sekai took her to a Burger shop and gave her a pep talk they then were joined by two members of Miyazato High School: Yomi Sakashita and Akira Suga. During the meeting Yomi and Gyanko kept arguing over dating. Sekai then decided to leave but before he left he got a word with Akira who told Sekai he has seen his martial arts and they wouldn't work on him. After Gyanko was defeated Sekai was enraged by the way Yomi was treating her, but after Akira slapped Yomi, Sekai calmed down. During the battle between Team Try Fighters and Miyazato High School, they split up. Sekai and Fumiana battled Akira and Yomi while Yuuma fought Shunsuke Sudou. After Yuuma and Shunsuke supposedly defeated each other simultaneously, Sekai and Fumina managed to defeat Akira and Yomi. Afterwards, Sekai is exhausted, only to find the match had not been called. He then saw the Mega Shiki was still operating and it attempted to defeat the Build Burning Gundam with a punch to the head. However, its arm shattered on contact, winning Team Try Fighters the match. As he is congratulated by Fumina and Yuuma, he collapses into their arms from exhaustion.
The next morning Sekai delivers the trophy to Fumina where he met her mother and was asked if he was her boyfriend. Sekai answered yes, assuming she meant a male friend. He then found out his sister had to get a Gunpla and enter a Gunpla beauty contest. Yumma told Sekai and Fumina to stay out of it as he was a Grand Prix winner and he will help build Mirai an amazing Gunpla. At the contest Sekai was not the least bit interested in the beauty contest but did cheer for his sister. After the first part he saw his sister being hit on by a Gundam music artist who made a bet that if he wins, he could take Mirai on a date. Sekai agreed but said he wouldn't win. The day of the race Sekai cheered for his sister but then showed some concern when his sister was being shot at as he thought it was a race not a fight. The singer's Turn A Gundam was too strong for Mirai and her main Gunpla was destroyed, but she had a trump card: the Petit Beargguy. She then used her Jigen Haoh School technique and defeated the Turn A in a way that made every man look on in shock, as she aimed for the cockpit (which was located in the crotch area). After she defeated the Turn A Gundam, Mirai ran towards the finish line, but unfortunately she tripped and lost to a Zaku. Sekai was pleased that his sister still defeated the singer and did her best. Mirai then offered to take Team Try Fighters out for a meal as a way of thanking them, much to Yuuma's dismay.
They then got taken by Mr. Ral to Yajima industries for training. During the road trip Fumina and Sekai were singing the first Gundam ZZ opening which annoyed Yuuma. After they arrived they met Team White Wolf who were very arrogant. Sekai decided to fight them but not in Gunpla battle, to which Mr. Ral replied, saying he disliked violence. However, their final team member walked in and told his team to behave themselves and he apologized to Team Try Fighters for his teams rudeness. He then challenged Team Try Fighters to a practice battle, which Sekai agreed to fight them in an hour but when they came back he saw Team White Wolf had been defeated by a Mysterious Gunpla that seemed to frighten Yuuma, who then charged into the arena and began attacking it. He attempted to take revenge for a battle 2 years ago prior, but he was defeated due to the difference in skill. Sekai then jumped in to protect Yuuma but he was also defeated. They were then saved by the arrival of Meijin Kawaguchi in his PF-78-3A Gundam Amazing Red Warrior. Sekai was then carried to the infirmary by Mr. Ral as Sekai had assimilated with his Gundam again, and suffered considerable damage. When Sekai woke up he went to fix his Gunpla, and entered the repair bay. As he entered, he felt the wind as he sees Shia Kijima who told him his Gunpla was beautiful leaving him at a loss for words.
Repairing the heavily damaged Build Burning Gundam, he is given advice by Shia, who helps him repair his Gunpla to a high level. She also helps him tune the Gunpla, improving its performance. He then participates in a Battle Royal with 3 other members of the other teams, including Wilfrid Kijima. During the fight, he and Wilfrid fight without weapons, and are equally matched. Sekai then learns a new technique, which Wilfrid then dodges. The attack destroys the moon in the stage, shocking everyone. After the match had ended, the Build Burning Gundam's arms shattered as it could not take the power of the new move. Yumma decided to upgrade the Build Burning into the Try Burning Gundam so that it can handle the amount of power.
With their new Gunpla, team Try Fighters easily won the first match of the championship. In the next match, they faced team SD-R from Toritsu Academy, representing Nagita. During the match, Try Burning was damaged and Sekai used its ultimate technique on Snibal-Drago-Gira before falling down. Fumina and Yumma then finished the battle.
Mirai is Sekai's older sister and his legal guardian. Sekai cares a lot for his sister and respects her greatly going as far as saying she is awesome in many ways.
Fumina and Sekai have a close friendship and it was Fumina who introduced Sekai to to Gunpla Battle. Sekai respects Fumina as a friend and teammate and wants to help her win the National Gunpla Battle Tournament.
Despite being teammates, Yuuma and Sekai are always seen arguing over Sekai's lack of Gunpla knowledge and his lack of care for his Gunpla. However, the two of them has shown to have great teamwork with each other and is willing to work together when required.
Sekai respects Mr. Ral as he is a world class fighter, he always listens to Ral's advice and will follow his strategies to win.
Sekai respects Gyanko as a rival but he is oblivious to her feelings for him. He went as far as to give her help and advice before a big fight in the Regional and was outraged when he saw her being mocked after she lost.
Sekai and Wilfried first met at the Yajima Trading Labs, resulting in a rivalry between the two of them from the respect of the opponent's skill, with both promising to fight one another at the Nationals again.
Sekai met Shia at Yajima Trading Labs while trying to repair the Build Burning Gundam. She soon developed an interest in him after noting his similarities to her brother.
- Sekai's habit of wearing his gi (marital art uniform) when fighting in formal Gunpla Battles is quite similar to Nils Neilsen's habit of wearing his martial arts uniform.
- Sekai's seat in the classroom is at the same position where China Kousaka sat 7 years ago.
- Similar to Mobile Suit Gundam 00's Graham Aker, Sekai appears to prefer wielding weapons with his left hand. When fighting unarmed however, he punches mainly with his right hand.
- Just like how Full Frontal is referred to as the "Second Coming of Char Aznable", Sekai was referred to as the "Second Coming of Reiji".
- During a Team Try Fighters practice battle, Sekai attempted to use a ranged Beam Spray Gun, but was unable to land any shots. This seems to imply Sekai has bad accuracy.
- Sekai's master is a homage to Domon Kasshu from Mobile Fighter G Gundam, resembling his overall features and looks. It is possible that Sekai's martial arts skills are based on Domon's own fighting style. He also seems to have Domon's attitude to fight strong opponents.
- Following that theme, the Jigen Haoh School's symbol (as shown on the side of Sekai's gi) looks quite similar to the God Gundam's Bakunetsu God Finger attack.
- In the first episode, after fighting a few street gang members, he shows a photo of his sister and asks them if they have seen her, in the same way Domon Kasshu did in G Gundam while looking for his brother.
- Sekai also has a tendency of activating a form of 'Meikyo Shisui', much like how Domon could after training with Schwarz Bruder.
- While narrating a letter to his master, Sekai asks if he is still training in the Guiana Highlands. Similarly, Domon originally trained under Master Asia in the Guiana Highlands.
- Even if it's coincidental, every Gundam Sekai has used has hinted a link to Domon. Aside from the Dom shell of Build Burning Gundam which has the first 3 letters on Domon's name, Musha Godmaru, Build Burning Gundam, Kamiki Burning Gundam and Try Burning Gundam showed similarities to Domon's God Gundam and Shining Gundam.
- Sekai's name means "world" in Japanese.