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Let There Be the Light of Science (この手に科学の灯を Kono Te ni Kagaku no Akari o) is the ninth episode of the Dr. Stone anime.


During their ramen patronage, the gang are approached by Gen Asagiri, a magician from Senku's time, who had been sent by Tsukasa to confirm Senku's death, but decides to give a false report instead. Using the successfully completed iron, Senku takes advantage of a sudden thunderstorm to turn it into powerful magnets. Using these, the gang build a power generator which they manage to convince Kinro and Ginro to operate, leading to the reinvention of the lightbulb.

Plot Details

A mysterious man approaches through the woods. Just outside the village, Senku is serving fox millet ramen that many of the villagers are enjoying. Chrome tries to share it with Kinro and Ginro but the latter refuses despite accepting a golden spear. Word of the foot even reaches the village chief. Senku plans to work with everyone who eats so they can power his furnace.

Gen Asagiri of the Tsukasa Empire.

The mysterious man from earlier sits down and has a bowl too. He mentions it's making him thirsty for a cola. Senku notices he uses a term from his time and Kohaku calls him out as an intruder. Kohaku, Kinro, and Ginro surround him with their weapons and question's if he's with Tsukasa. The boy claims he's been alone ever since he was unpetrified.

Senku recognizes the man as Asagiri Gen, the mentalist who used to write books. The magician apologizes for taking some ramen and asks the guards to lower their weapons. Kohaku doesn't believe a word he says as Asagiri tries to explain himself. Senku says it doesn't matter and makes everyone work on the iron mill furnace. While Asagiri is working hard, Senku takes advantage of his exhaustion and asks him about Taiju. Asagiri admits he's with Tsukasa and claims thing have changed now that he's seen them create iron.

Senku creates a magnet using lightning.

Asagiri admits Tsukasa's side looks better for now and he simply sides with whoever will win. Senku believes he can win him over and starts working to prepare a generator. A thunderstorm hits and Senku gets his group ready to catch some lightning. They start the process but are interrupted by the untimely arrival of Magma, the village brute. Asagiri manages to turn them back around by using some convincing magic.

Senku's group travels to the bald mount and prepares to harness the lightning to create a magnet. The lightning closes in faster than expected, so they don't have time to build a tower. Kohaku steals Ginro's speer and turns it into a lightning rod. Lightning strikes the rod wrapped in copper and successfully transforms it into a strong magnet.

Senku lights up the darkness for the first time in 3,700 years.

Kohaku holds the poles backward and mistakenly thinks they failed to make magnets. Senku corrects her and Chrome gets pumped to make electricity. Asagiri asks what kind of generator Senku plans on building and isn't surprised to learn it's going to be man-powered. Together, they spend today creating a dual crank power generator. Asagiri convinces Ginro and Kinro to power it for them because they need a pair in perfect sync. Despite sticking around this long, Asagiri really questions if Senku can use electricity.

Senku asks Chrome if he's afraid at night because of its dark. Edison created the lightbulb and conquered the 24 hour day. Senku believes there is no darkness in him time and humanity defeated the night using science. He uses a bamboo string to imitate a lightbulb and lights up the night for the first time in 3,700 years.





  • Iron Mill Furnance, Level 2
  • Iron
  • Copper Wire
  • Powerful Magnets
  • Power Generator
  • Lightbulb

Anime to Manga Differences

  • In the manga, it was Kohaku that teased Kinro about accepting the gold spear and not food while it is replaced with Chrome in the anime.
  • The detail about how level 2 pump and electric generator are omitted in the anime.
  • The imagination of Gen when thinking about either joining Tsukasa or Senku is changed from Gen bathing in a balance with idols while it is in a hot spring in the anime.
  • Panels showing light bulb and Thomas Edison are omitted in the anime.
  • A short backstory about Senku during primary school is omitted in this episode.

Site Navigation

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Story Arcs
Prologue Saga
Stone Formula Arc
Chapters 1234
Episodes 12
Vs. Tsukasa Arc
Chapters 56789101112
Episodes 345
Ishigami Village Saga
Kingdom of Science Arc
Chapters 131415161718192021222324252627282930313233
Episodes 5678910111213
Village Games Arc
Chapters 34353637383940
Episodes 131415
Village Origins Arc
Chapters 4142434445
Episodes 1617
Stone Wars Saga
Vs. Hyoga Arc
Chapters 4647484950
Episodes 1819
Communications Arc
Chapters 5152535455565758596061626364656667686970717273747576777879808182
Episodes 20212223242526272829303132333435
Source of the Petrification Saga
Age of Exploration Arc
Chapters 8384858687888990919293949596979899 100
Episodes 35
Treasure Island Arc
Chapters 101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138
The Truth of the Petrification Saga
New America City Arc
Chapters 139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169
South America Arc
Chapters 170171172173174175176177178179180181182183184185186187188189190191192193
New Stone World Arc
Chapters 194195196197198199200
Globetrotting Arc
Chapters 201202203204205206207208209210211212
Stone to Space Saga