Dr. Stone season 4 episode 7: Senku and Xeno's history is revealed

Following the tease of Senku Ishigami and Dr. Xeno’s connection, Dr. Stone season 4 episode 7 was expected to fully elaborate on their implicit history with each other. Officially released on Thursday, February 20, 2025, the installment did indeed show their full history with each other, sticking with them into the moment they each awoke in the Stone World.

In the process, Dr. Stone season 4 episode 7 also revealed the relationship Xeno had with Senku’s father, Byakuya, as a NASA scientist and astronaut. Finally, the installment also clarified how Xeno was able to gather such strong and influential allies like Stanley and Luna, given what happened at the time of the Petrification.

Dr. Stone season 4 episode 7 fully explores Senku and Xeno’s mentor-student relationship

Brief episode recap

Expand Tweet

Dr. Stone season 4 episode 7 began with a flashback to Senku Ishigami at age 10, when Taiju and he were trying to launch a rocket of their own. After causing a massive explosion, Senku went back to the drawing board, studying English papers by using a translation dictionary.

He also sent emails to several scientists asking for help and advice, outlining his experiments and the data he had collected so far.

One email went to a NASA team which Dr. Xeno Houston Wingfield was a part of, aged 20 at the time. Xeno emailed Senku back, providing him with resources and even referring to him as “Dr. Senku.”

Eventually, Senku flew over to the United States to see his father Byakuya, training to be a NASA astronaut. However, Senku made it clear he only visited to grab the credit card Byakuya was issued, flying back to Japan with it to buy what Xeno instructed him to.

Dr. Stone season 4 episode 7 also saw Senku reveal he had been taking what he called online classes with Dr. Xeno, who was also communicative with Senku. Their communications continued as Senku continued experimenting, with Xeno also struggling at work and having his project ideas rejected.

Xeno also explained to Senku how he viewed science as a power that can dominate the world, with Senku arguing that science is about uncovering secrets.

Byakuya and Senku's relationship is also a major highlight of Dr. Stone season 4 episode 7 (Image via TMS Entertainment)

The two were antithetical in their perceptions of what science is and what it should be used for. Xeno was one day asked what he’d do if he was sent back to the Stone Age, saying he’d make scientific weapons from scratch and rule as a dictator.

Byakuya argued that another scientist would show up, someone like his son, who wanted to know everything about everything. Xeno simply said he’d eliminate anyone who stood in his way.

Dr. Stone season 4 episode 7 then shifted focus to Senku, who still spoke with Xeno as a teenager and was getting advice from him on his rocket.

Senku then visited Africa following Xeno’s advice, and eventually returned to America to see his adoptive father Byakuya, when Byakuya’s credit card had expired. Xeno overheard Byakuya say his son’s name was Senku, with Xeno seemingly putting it all together.

He likewise found Senku admiring a rocket, standing silently with him before Byakuya interrupted and he walked away. Senku left Japan shortly thereafter, with the focus then shifting to the night before the Petrification.

Both Senku and Xeno were seen studying the petrified swallow populations, with it being revealed that Senku was responsible for the data analysis, which put Xeno on the issue.

Expand Tweet

Dr. Stone season 4 episode 7 saw Xeno and others studying a petrified swallow at the United States’ Center for Disease Control. The swallows’ organs were confirmed to be intact inside, with other signs indicating that they were still alive.

At the same time, Senku was also studying his own petrified swallow. This shifted focus into the first episode’s opening scenes, which then transitioned into what Xeno was doing in America at that time.

Stanley Snyder was introduced here, as were several others who would be seen working under Xeno in the Stone World. He confirmed to Stanley and the others that the swallow was still alive, as evidenced by the presence of brain waves in its head.

This led Stanley to conclude that one could still survive if they were attacked by the weapon that caused Petrification. As Luna, Max, and Carlos were shown to be present, the Petrification Beam appeared.

Dr. Stone season 4 episode 7 then jumped ahead in time to Stanley and others trying to stay awake within their petrified bodies. Eventually, a rain came which caused Xeno’s petrified body to begin drifting towards a nearby source of nitric acid.

Focus also shifted back to Senku, showing that he was counting the seconds to keep himself conscious in Japan. The episode ended with Senku and Xeno each unpetrifying at the same time.

Final thoughts

Dr. Stone season 4 episode 7 also explains how the likes of Stanley, Luna, and others came to be allied with Xeno (Image via TMS Entertainment)

Despite being a flashback episode in its entirety, the seventh episode of Dr. Stone’s fourth season is still an enjoyable and informative watch. Likewise, the fact that it fully elaborates on Senku and co’s relationship sets up a return to the present in the next release, which should then see the action officially begin.

From here, fans can expect Xeno to discover the truth about Senku eventually, leading to a climactic confrontation between them later on in the season.