The episode begins with Senku and his team completing the construction of their ship, which they name the Science Vessel Perseus, on September 10th, 5741 AD. The ship is a significant scientific achievement after a year of hard work. Once the ship is ready, everyone boards it in preparation for their journey.

Ryusui, the skilled navigator, initially declines to set sail due to fear, but Ginro, who had also been hesitant, suddenly changes his mind at the last moment. Ginro dramatically dives into the water and swims after the ship in an attempt to board it. This act is partly motivated by his desire to impress the women on board. Taiju, demonstrating his strong swimming ability, quickly follows and helps Ginro onto the ship, much to Ginro's embarrassment.

As the ship finally sets sail, Senku announces that their first destination will not be the other side of the world as initially planned, but rather a place called Treasure Island. This island is significant because it is where Senku's father and other astronaut survivors first landed after the petrification event.

The crew begins their voyage aboard the Perseus, leaving behind the village and many of their people. This decision to take only a select group on the ship, including fighters and scientists, leaves the village somewhat undermanned, raising concerns about the safety and sustainability of those left behind.

During the journey, the crew encounters various challenges related to the ship's operation and the unknowns of the sea. Ryusui takes charge of navigating the vessel, while Senku and the others prepare for the scientific and exploratory tasks ahead.

The episode ends with the Perseus underway, the crew focused on their mission to reach Treasure Island and uncover the mysteries related to the petrification event and the astronaut survivors. The mood is a mix of excitement and tension as they embark on this new chapter of their adventure.

At the end of Dr. STONE Season 3, Episode 5, titled "Science Vessel Perseus," the main group successfully boards the newly built ship, the Perseus. Ryuusui begins to set sail, initially hesitant but ultimately leading the voyage. Ginro, who was afraid at first, dramatically dives into the water to chase after the ship and is pulled aboard by Taiju. Senku announces their first destination will be Treasure Island, where his father and other astronaut survivors landed, marking the start of their new journey.

The episode concludes with a detailed sequence of events:

The scene opens with the final preparations for departure aboard the Science Vessel Perseus. The ship, a product of intense scientific and engineering effort, is now ready to sail. Ryuusui, the skilled navigator, takes command but initially declines to set sail due to fear. This hesitation reflects his internal conflict about the dangers ahead.

Meanwhile, Ginro, one of the fighters, is reluctant to board the ship. His fear is palpable, and he initially refuses to come aboard. However, as the ship begins to pull away from the shore, Ginro makes a show of having second thoughts. In a dramatic and somewhat comedic moment, he dives into the water to swim after the ship, intending to appear brave in front of the women on board. Unexpectedly, Taiju, known for his physical strength and swimming ability, quickly follows and hauls Ginro onto the ship, much to Ginro's embarrassment.

Once everyone is aboard, Ryuusui overcomes his fear and officially sets sail. Senku then addresses the group, informing them that their first destination will not be the far side of the world as initially thought, but rather Treasure Island. This island is significant because it is where Senku's father and other astronauts survived after the petrification event. This revelation sets the stage for the next phase of their adventure.

The episode closes with the ship moving steadily away from the shore, symbolizing the Kingdom of Science's bold step into the unknown. The group's departure is bittersweet, as it leaves behind the village somewhat undermanned, with many fighters, scientists, and craftsmen aboard the ship. This decision hints at potential challenges for those remaining.

Regarding the main characters' fates at this episode's end:

• Ryuusui overcomes his fear and takes on the role of captain, steering the Perseus into uncharted waters.
• Ginro conquers his initial fear, albeit in a showy manner, and is safely aboard thanks to Taiju.
• Taiju remains a strong and dependable presence, ensuring Ginro's safety.
• Senku leads the group with clear scientific purpose, setting their course toward Treasure Island.
• Other key members aboard the ship include scientists and fighters essential for the journey, though the episode focuses mainly on these characters.

This ending emphasizes the themes of courage, teamwork, and the pursuit of knowledge, as the Kingdom of Science embarks on a new chapter of exploration and discovery.

Dr. STONE Season 3, Episode 5 ("Science Vessel Perseus") does not have a post-credit scene. The episode ends with the completed ship, Science Vessel Perseus, setting sail under Ryusui's command, with Ginro diving in to board at the last moment, and Senku announcing their first destination as Treasure Island, where his father and other astronaut survivors first landed. There is no mention or indication of any additional scene after the credits in the available episode recaps, transcripts, or reactions.

In episode 5, 'Science Vessel Perseus,' Senku and his team encountered significant difficulties due to the lack of high-precision tooling. Kaseki, the master craftsman, struggled with parts being too long, too short, or misaligned, which made assembling the massive ship very challenging. Despite Senku's reassurance, Kaseki was at his wit's end, highlighting the complexity of building such an advanced vessel with limited tools.

Senku's primary goal in episode 5 is to find a treasure chest left on the island where his father, Byakuya, and his crew first landed thousands of years ago. This chest is believed to contain key secrets and truths about the current state of humanity and the petrification phenomenon. Finding it is crucial for unlocking greater information that could help locate the source of the petrification beam, tying back to Senku's past and the overarching mystery of the series.

The mysterious enemy known as 'Why-Man' is referenced through a foreign Morse code signal repeatedly sending the message 'Why?'. Senku and his team suspect this entity might be behind the petrification of humanity. They decide to call this unknown adversary 'Why-Man' and plan to search across the ocean to find and confront this entity. This plot element is a driving force for their expedition aboard the Perseus.

Leading up to and during episode 5, Senku and his team made significant scientific progress, including developing radar and sonar systems to search the air and ocean, mining and transporting iron to produce steel engines for the ship, and rapidly advancing their technological capabilities. These achievements allowed them to complete the Perseus and set sail on their expedition, marking a new era of scientific exploration in the series.

During the launch of the Perseus in episode 5, the characters exhibit a mix of excitement, determination, and some tension. Kaseki feels stressed and overwhelmed by the technical challenges of assembling the ship. Senku remains confident and reassuring, pushing forward with the mission. The crew shares a sense of adventure and camaraderie, with moments of humor and lightheartedness, such as Chrome enjoying the minecart ride. The episode balances the epic tone of the journey with personal stakes tied to Senku's past and the mystery they seek to solve.

Dr. STONE Season 3, Episode 5 ("Science Vessel Perseus") is generally family-friendly but is rated TV-14, indicating it is suitable for teens and older children with parental guidance. The content includes mild violence and mild profanity, with no strong sexual content or graphic scenes.

Potentially objectionable or upsetting aspects for children or sensitive viewers include:

• Mild violence and action scenes typical of adventure anime, but nothing excessively graphic or gory.
• Some mild profanity such as "shit," "dick," and "crap," though used sparingly.
• Occasional emotional intensity or moments that might be upsetting, such as character conflicts or tense situations, but nothing extreme or horror-like.
• Mild references to alcohol and medicine use (e.g., antibiotics), but no drug abuse or smoking.

There are no significant sexual or nudity scenes, and frightening scenes are mild and not likely to be traumatic. Overall, the episode is suitable for older children and teens, but very young or sensitive children might need supervision due to mild violence and language.