Chapter 4 is titled "Family Argument".
Daruma speaks with Hachimaru's father about the danger the galaxy is in and his son's place in the battle against it. A lack of faith and a crippling fear prevents his dad from trusting his son to leave home. Hachimaru returns from his adventure with Nanashi and gets into an argument about the subject of going out into the world. Daruma then makes Hachimaru an offer, and he must decide if he will keep his life the same or change it forever.
Hachimaru enjoys the flight back home on Hayataro's back. He suggests they try going into space, but Hayataro feels they aren't ready, so Hachimaru asks to go back home. At home Hachimaru's father is surprised that Daruma was holding onto the Dojikiri Takatsuna. Daruma's understanding of the Samurai Soul's power and the fact that his Handle Bone is worthy enough to shape it proves to him that he is an above average Samurai. Daruma repeats his demand to know who he and Hachimaru are, but Hachimaru's dad counters that a proper Samurai would reveal his identity first.
Daruma exposes his Key and reveals his true name. Hachimaru's father is shocked to see an authentic Kongo-Yasha sight, and realizes he is in the presence of a legendary Samurai, only to be unimpressed by his current form. After getting over the response to his appearance, Daruma expresses interest of his host's knowledge about Samurai who aks what such a famous Samurai is doing on such an ordinary world. Admitting he is a bad liar, Daruma responds with complete transparence. He explains that the galaxy in is danger of being destroyed, and the only thing that can prevent this is a special box locked by seven specific Samurai Keys. He has spent 50 years searching for the Keys, and Hachimaru's dad realizes that his child is one such Key. Despite the danger to the galaxy, he refuses to let his child leave with him. Daruma senses that he isn't surprised by the danger he just explained, and asks if he already knows what he is talking about. Ignoring the question, Hachimaru's dad adamantly refuses letting Daruma take his son, still believing he needs to be protected. The cat Samurai counters that Fudo Myo-o ordained that Hachimaru become one who protect others, and he needs to have more faith in his son.
Before they can keep talking, Hachimaru arrives and starts talking about what happened while he was out. His father chastises him for going too far away as Hachimaru decides to fly off again. His father refuses to let him and the two argue over whether or not he can handle the dangers of the outside world. The argument reaches a boiling point when Hachimaru accuses his dad of purposely leaving the mobile life support unit he promised to build incomplete. He claims that his father is being insensitive to his desire to see the world despite the danger. Though moved, he orders Hachimaru to stay near the house and demands that Daruma leave. As he walks away, Hachimaru calls for Daruma to back him up, only to see that he has fallen asleep.
Going inside, Hachimaru's dad recalls his son's youth, specifically a time when he was watching video of a boy flying a ship. He asks his child if wants to ride one, and he defensively claims he doesn't. Knowing the boy was fronting, he was inspired to build the mobile support unit for him. He is then shaken by the memory of a ominous masked man vowing to hunt him down. Torn between empathy and fear, he laments his indecisiveness.
Outside, Hachimaru worries that he went overboard with his words, understanding why his dad is so worried for him. He wonders if getting stronger will help soothe his dad's fears. Daruma, now awake again, tells him that a Samurai must make their own decisions. Stepping onto the grass, he asks Hachimaru what his favorite number is. Though confused, he settles on eight, since "hachi" (
Daruma tells Hachimaru again that Samurai decide things on their own. He reveals that he is leaving and offers a challenge. If Hachimaru crosses the line he cut in the ground, Daruma agrees to teach him everything he knows about the Kongo-Yasha Style: if not, he can stay with his dad and live in peace. Hachimaru hesitates for a moment, then makes his choice. Since he already acknowledged Daruma as his master, he crosses the line with Hayataro.