Dr. Stone season 4 episode 9: Senku's status confirmed while Chrome steps up as a scientist

Dr. Stone season 4 episode 9 was expected to focus primarily on elaborating Senku Ishigami’s condition after the shot Stanley Snyder landed on him last week. Officially released on Thursday, March 6, 2025, the installment did indeed elaborate Senku’s status, which may not be as optimistic as fans were expecting.

Dr. Stone season 4 episode 9 also sees Tsukasa Shishio’s team meet up with Chrome and Kohaku, officially starting their preparations to invade Dr. Xeno Houston Wingfield’s compound. Likewise, Chrome steps up in a major way, being set up for his biggest moment since he escaped Tsukasa’s Empire of Might in season 2.

Dr. Stone season 4 episode 9 sets Chrome up for greatness as Senku is sidelined

Brief episode recap

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Dr. Stone season 4 episode 9 began with the Kingdom of Science reacting to Stanley Snyder’s gunshot in chaos and confusion. Taiju Oki and François rush to Senku Ishigami’s side, finding blood pouring out from both his mouth and his torso. Focus then shifts to Stanley jumping down and telling Max and Carlos the mission is a success. He tells the two to remain and observe Senku’s group as he returns to Dr. Xeno, indifferent about Luna Wright’s ultimate fate.

Ryusui Nanami, meanwhile, takes charge as the others panic about Senku being dead. He emphasizes that they have an opportunity to take advantage of the enemy thinking Senku was dead. Senku was shown to be alive, with François and Taiju providing first aid while sharing his softly spoken words. Senku then revealed he knew Stanley would aim for his chest in an attempt to allow him to pass on the recipe for the Revival Fluid.

Dr. Stone season 4 episode 9 sees Luna watch all this unfold, visibly impressed by the group’s coordination and dedication. Senku passes out, with François saying they need a doctor. Luna tried to use her memory of medical skills to check Senku’s blood pressure, revealing she was a med student before the Petrification. While she flunked out of med school, Taiju nevertheless begs her to save Senku with tears in his eyes.

Luna's brief stint in medical school proves integral to giving Senku first aid in Dr. Stone season 4 episode 9 (Image via TMS Entertainment)

Focus then shifts to Chrome and Kohaku at what appears to be the next sunrise. The pair are scouting Dr. Xeno Houston Wingfield’s compound and finding no safe way to infiltrate. Tsukasa Shishio’s team then arrives, surprising the pair before they immediately begin assessing a way in. Ukyo Saionji points out that their mission isn’t just about infiltrating, but capturing Dr. Xeno and leaving, with Tsukasa suggesting they dig their way in.

Hyoga agrees, while Kohaku and Chrome express confusion. Hyoga adds that they’ll need Senku’s help as Ukyo and Suika are in apparent shock at the suggestion. Dr. Stone season 4 episode 9 saw them get a call from Ryusui, who gave a coded message informing them of Senku’s current condition and recent events. This likewise meant they couldn’t count on Senku for digging tools to help, with Senku instead making it clear that he trusts Chrome to get it done.

Senku is seen telling Chrome that he’s the scientist, calling him Dr. Chrome as he’s seen with a determined look on his face. Chrome reviewed the situation and their needs in his head before questioning if he truly can do this. However, he quickly worked through this, promising his allies that they could count on him. Tsukasa estimated they’ll need two weeks minimum to complete preparations, while Ryusui reviewed the current situation with those on the Perseus.

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Dr. Stone season 4 episode 9 saw Ryusui suggest toying with them to make them think it’s safer to wait before taking action against them. It was then revealed Ukyo was carrying the real Medusa Device with him, attaching it to an arrow and firing it at Dr. Xeno’s front door. Ryusui explains that doing so will play into Dr. Xeno’s scientific curiosity, and intimidate him via Gen Asagiri’s fib of an explanation on it to Xeno.

Gen likewise understood the plan and executed it perfectly. However, one of Xeno’s subordinates points out that Gen already lied to them about Taiju being the science leader. However, Xeno took caution with the Device nonetheless as Stanley returned and demanded answers on how to use the Device. Gen lied and said that only the battle team knew that, adding that the beam it emits is inescapable like what caused the Petrification.

Dr. Stone season 4 episode 9 saw Stanley and Xeno depart after hearing this, discussing something referred to as the “you-know-what” which would render Senku and co defenseless. They then addressed the character who pointed out Gen’s untruthfulness earlier as Dr. Brody Dudley, asking him when “it” would be ready. Brody laughed and answered that he only needed two more weeks to “have it all” ready.

Chrome coming through in a major way proves Senku was right to trust him in Dr. Stone season 4 episode 9 (Image via TMS Entertainment)

Gen was brought along for this conversation, but unable to hear it due to Xeno’s strong female subordinate covering his ears. Gen muses on what it could be, while Chrome declared the race officially on between each side’s science users. Chrome first used trigonometry to figure out how far they had to dig and at what angle, eventually arriving at the answer.

As Chrome and co continued to work on their goal, Senku was shown being treated onboard the Perseus. Dr. Stone season 4 episode 9 ended with Chrome revealing he had effectively designed a modern-day drill to use to dig into Xeno’s compound, even naming it as such without realizing.

In summation

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Season 4 episode 9 primarily focuses on setting up the war between the two Kingdoms of Science coming to a head as each gets to work on their own secretive plans. Likewise, Xeno’s unknown trump card is presented in a terrifying way, being implied as all he and his allies need to secure victory. Resultantly, even more pressure fails on Chrome and co to capture the enemy’s king before their own group is put in checkmate.