Gundam Build Fighters

Sei Iori aims to participate in the Gunpla Battle Championship World Tournament, but despite his skill at building models, he can't control them in battle. Then Sazaki challenges him to a Gunpla battle in order to get his hands on Sei's high-performance Gunpla. Sei accepts the battle, thinking that if he can't even beat Sazaki, then he'd be defeated instantly if he made it to the championship. But Sei is backed into a corner by Sazaki's overbearing fighting style until the appearance of Reiji, a mysterious boy who he met earlier that day. Even though Reiji has never used Gunpla before, he overwhelms Sazaki's Gunpla with his superb control technique. Sei builds, and Reiji battles. Thus the Gundam Build Fighters are born!

Having met Sei by chance, the mysterious boy Reiji insists on staying at his home and somehow even ends up coming to his school. And when Gonda, a student council executive, tries to kick out this intruder, Reiji turns the tables on him as well. Tatsuya Yuuki, the student council president and head of the model-building club, attempts to resolve the situation by saying that he invited Reiji to join the club. But Gonda, having lost face in front of the other students, challenges Reiji to a Gunpla battle purely for revenge. Using Sei's Build Strike Gundam, Reiji wins a total victory in his battle with Gonda. Then a crimson Gunpla appears before them both—the Zaku Amazing!

Sei and Reiji have now witnessed the overwhelmingly superior power of Tatsuya Yuuki's Zaku Amazing. To prepare for the day when he'll face Yuuki again in the championship, Sei secludes himself in his workshop to complete the Full Package equipment for his Build Strike. Meanwhile, Reiji goes out into the city at night and heads for a certain place—a store where men with years of Gunpla experience meet night after night to fight battles. Reiji challenges the men just for the sake of combat practice, and easily defeats his opponents. But then Ricardo Fellini, an Italian Gunpla battle fighter, appears before him! And on the day of the championship, Sei has somehow completed the Build Strike, but Reiji is nowhere to be found...

Sei falls in love with a mysterious girl who is into Gunpla, unaware of her true intentions in Gunpla Battle.

Sei and China meet Mao Yasaka, a young Gunpla Fighter from Kansai Prefecture.

When Yuuki suddenly bows out of competition and takes an indefinite leave from school, Reiji begins to doubt his purpose in Gunpla Battle.

As a reward for winning the Gunpla Battle Japan 3rd Block Championship, Sei and Reiji, along with China, Rinko, and Ral-san, take a vacation at a beachfront inn. But their vacation is cut short by a former Gunpla Builder who threatens the innkeeper to give him their property.

Nils Nielsen, a 13-year-old genius, joins the American Qualifying Round of the World Championship to learn more about the secrets of Plavsky particles. Meanwhile, in Finland, Team Nemesis receives a new fighter named Aila Jyrkiainen from the Flana Institute. Nils swiftly defeated Greco Logan in the American Qualifying Round of the World Championship.

China completes her Gunpla Beargguy III (San), and when a painting of it wins the grand prize at the local art exhibit, her rival Caroline Yajima issues her a Gunpla challenge.