The year 2006. Two brothers, Nanba Mutta (age 12) and Hibito (age 9), happen to spot a UFO headed for the moon. The experience inspires them to make a certain promise.

With his mother's assistance and Hibito's encouragement, Mutta has been accepted for the New Astronaut Selection Exam. However, unsure of his next step, he visits Sharon, who works at a nearby observatory. After receiving advice from Sharon, Mutta is finally able to make up his mind.

After advancing to the second exam, Mutta realizes that the other applicants are much better prepared than he is. Desperate to prove himself, he stakes everything on the lung capacity test, as he has confidence in his trumpet-trained lungs. However, as the other applicants drop out, he finds himself in a heated battle with Itou Serika. Who will come out on top?

After a long week, only the final interview remains in the second JAXA exam. Mutta is drawing attention as Nanba Hibito's older brother, but he insists he won't spend his entire life as Nanba Hibito's big brother.

After completing the second JAXA exam, Hibito invites Mutta for a free trip to Houston, Texas, through NASA's family support program. Upon arrival, he finds himself chased by a pug named Apo, and is then reunited with Hibito. However, Hibito expresses disappointment.

Mutta has arrived in America, but he's off to a rocky start with Hibito. Meanwhile, his future as an astronaut is in jeopardy because the headbutt incident has been brought to JAXA's attention.

After learning that his former boss has told JAXA about the headbutt incident, Mutta has given up hope on passing the exam. To cope, Mutta falls back on his childhood habit of multitasking like crazy when something bad happens.

When the robber known as the fire extinguisher man strikes the restaurant where Mutta is, he's in trouble. But once the dust settles, Mutta has become a national hero for capturing the criminal. However, it appears there's more to the story.

After passing the second JAXA exam, Mutta returns to Japan for the third. He's happy about the exam result, but on the flight back, a nightmare leaves him rattled. This is due to the letters from Hibito that he discovered before leaving.

Mutta has learned that Kenji and Serika have strong reasons to become astronauts, while Mutta is simply trying to achieve a childhood dream. This causes Mutta to begin to question himself.

The third exam will take two weeks. Mutta and the other candidates are transported via sealed bus to a large, barren facility. Then they are led to an area that is known as the last room.

The fifteen remaining candidates have been divided into three teams of five. Each team will spend two weeks inside a sealed box, while completing various tasks. The first task is to determine the time.

The sealed box teams are assigned more tasks. These include Running Math, five minutes of mental math while running, and a typing test. Next, they're asked to write a letter of protest to a journalist who is criticizing government funding for space exploration.

After five days in their sealed boxes, each team is exhibiting a pronounced personality. Mutta's Team A is rowdy, while Team C is quiet. However, Kenji's Team B appears to be a little gloomy.

The exam in the sealed box is halfway over. Mutta's Team A suffered an accident when Fukuda's glasses were broken. But Furuya, the one who broke them, requested a new pair. Meanwhile, Team B must deal with an alarm going off in the middle of the night.

The third exam is halfway over. Mutta works on a completely white puzzle as he ponders why Fukuda-san would break the only clock in the sealed box.

The third exam inside the sealed boxes has been underway for ten days. Each team has been experiencing unexpected problems, such as broken clocks and mysterious alarms that ring in the middle of the night. However, Mutta soon realizes who is actually responsible.

The candidates have only a few days left in the sealed boxes. JAXA has been using green cards to create trouble, gauging each member's ability to respond to stress and trouble.

The teams have two days left in the sealed boxes. Mission Control has deliberately not given certain members of Kenji's Team B any green cards, leading to paranoia. Meanwhile, in Team A, Mutta announces that he has good news, bad news, and dicey news.

It's their final day in the sealed box. Mutta has enjoyed his two weeks with the team, and he wishes to avert ruining their bond, as they make their final decision.

With the third exam finally over, Furuya takes the opportunity to visit the man who made his dream possible.

The third astronaut selection exam has finally ended. Team A used rock-paper-scissors to select two members. Whose dreams are still alive?

Mutta has been picked to go to Houston for the final astronaut selection exam. But because his selection means that Kenji wasn't chosen, he has mixed feelings.

The final exam is set to take place in two months. Mutta heads to Houston, ahead of the other candidates to look after Apo and tour the Johnson Space Center. Meanwhile, Hibito is training hard for his lunar mission.

With the final astronaut selection exam coming up, Mutta heads to Houston. However, Jennifer has some ominous news.

Seven days remain before Hibito takes off on a journey to become the first Japanese person to walk on the moon. Meanwhile, Mutta prepares for the final astronaut selection exam at Johnson Space Center.

The final NASA interview was a decoy to trick the candidates into relaxing, so the astronauts could evaluate them. However, the candidates have yet to realize this.

Two days are left before launch. First, the lunar lander Artemis goes into space on Mars V. Afterwards, Hibito and the rest of the crew will head into space on Mars I.

It's finally the day of the launch, but the weather doesn't look good. On top of that, Apo's run off, so Mutta has to go find him. While searching for Apo, Mutta comes across a suspicious old man.

Mutta, Apo, and the strange old man watch as Hibito launches off into space. Afterwards, Mutta reminisces about the road taken by Hibito to reach this point.

Hibito has made it safely into space, and he's on his way to the moon. Meanwhile, Mutta runs into Azuma and his family, and he decides to approach them.

Hibito and the CES-51 crew finally land on the moon. However, Mutta is worried that Hibito will embarrass their country when he takes his first step.

Hibito and the CES-51 crew have landed on the moon. Meanwhile, Mutta has returned to Japan to await his final exam results. He's especially concerned about using up his luck before the results are announced.

JAXA has begun announcing the results of the final astronaut selection exam. Makabe Kenji receives the first phone call. As Kenji waits to learn his fate, he reflects on his motivation for wanting to be an astronaut.

While Mutta waits to hear if he will become an astronaut, Kenji has received good news. The next candidate to get a call is Serika.

Two hours have passed since JAXA was supposed to notify the candidates, and Mutta hasn't received a call. When the phone finally rings, he's told to go to a nearby park. What will his fate be?

After a long wait, Mutta learns that he passed the final exam. With no time to enjoy the moment, he is immediately whisked to the press conference, where the other new astronauts wait.

Mutta has begun his life as an astronaut. First, he must undergo a month of JAXA training and orientation. Meanwhile, Hibito and Damian head out in a lunar rover to track down a missing probe.

Damian and Hibito leave Moonbase in search of a missing unmanned probe. However, an accident occurs, stranding them inside a ravine.

After a buggy accident, Hibito and Damian are stuck at the bottom of a ravine. Damian's spacesuit is damaged, and he's losing body heat quickly. The odds are against them, but Hibito decides that the unmanned drone Gibson is their key out.

Hibito manages to bring Damian back to the surface by using Gibson, but he's running out of time, as his oxygen supply dwindles. Will Freddy and Buddy find him in time?

Hibito is able to save Damian, but he's running out of oxygen. Freddy and Buddy are trying to catch him, but they won't arrive before his oxygen depletes. Is this the end?

Oxygen generation system Brian arrives just in time to save Hibito. Once he and Damian are rescued and back at Moonbase, he reflects on the astronauts who saved him.

Mutta and the other astronaut candidates have finally finished their Japanese training. Before they head to Houston, they receive a gift from Director Nasuda.

The JAXA astronaut candidates head to Houston, to begin training at NASA. However, Murakami-san appears to have a surprise in store for Mutta.

Mutta and the other astronaut candidates have arrived in Houston to begin training at NASA. First up is a social event to meet the other astronaut candidates from around the world.

The first astronaut candidate task is undergoing a survival training course consisting of a six-day trek through the desert. Meanwhile, Mutta is still worried about Amanti's reaction after she read his fortune.

The astronaut candidates continue their survival training in the desert. Team E has fallen behind the others, but after Nitta takes the lead, they try to pick up the pace.

As the survival training draws to a close, Nitta suddenly tells the team he needs to backtrack due to losing his cell phone, but Mutta stops him. However, Mutta appears to have an idea in mind.

Mutta and Nitta backtrack through the desert, looking for Nitta's cell phone. But Nitta cannot find it in time to answer his little brother's call. Has he lost another chance to reach him?