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.

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.

Mutta, Hibito and Serika accompany Sharon to a neurologist, where Serika fears she may be suffering from amyotrophic lateral sclerosis just like her father. As Sharon is admitted for more tests, Serika explains the details of ALS to Mutta, who is shocked to learn that it may one day kill her. As such, Mutta finds himself unable to concentrate on his written test and scores terribly. Following her examinations, in which she is properly diagnosed with ALS, Sharon is visited by Serika, who tells her about her father and motivates her to work hard on her research despite her illness. As Sharon heads back towards Japan, Mutta reaffirms his promise to help build her telescope. Later, Serika tells Mutta about a similar promise she made to get up to the ISS and develop a treatment for ALS.