Dr. Stone Wiki
Dr. Stone Wiki

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, Gen Asagiri, a magician from Senku's time, who had been sent by Tsukasa to confirm Senku's death, approaches the gang, 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 builds 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 serves fox millet ramen, which many of the villagers enjoy. 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 first appearace

Gen Asagiri of the Tsukasa Empire.

The mysterious man from earlier sits down and has a bowl too. He mentions that it's making him thirsty for 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 if he's with Tsukasa. The boy claims he's been alone ever since he was unpetrified.

Senku recognizes the man as Gen Asagiri, the mentalist who used to author 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 Gen tries to explain himself. Senku says it doesn't matter and makes everyone work on the iron mill furnace. While Gen is working hard, Senku takes advantage of his exhaustion and asks him about Taiju. Gen admits he's with Tsukasa and claims things have changed now that he's seen them create iron.

The God of Lightning Descends

Senku creates a magnet using lightning.

Gen 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 the untimely arrival of Magma, the village brute, interrupts them. Gen 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 spear and turns it into a lightning rod. Lightning strikes the rod wrapped in copper and successfully transforms it into a strong magnet.

The Light Returns

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. Gen asks what kind of generator Senku plans on building and isn't surprised to learn it's going to be man-powered. Together, they spent today creating a dual-crank power generator. Gen convinces Ginro and Kinro to power it for them because they need a pair in perfect sync. Despite sticking around this long, Gen really questions if Senku can use electricity.

Senku asks Chrome if he's afraid at night because of the darkness. Edison created the lightbulb and conquered the 24-hour day. Senku believes there is no darkness in his 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 Furnace, 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 details about the 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 bulbs and Thomas Edison are omitted in the anime.
  • A short backstory about Senku during primary school is omitted in this episode.

Site Navigation[]

[v  e]
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 35Ryusui3637383940
Treasure Island Arc
Chapters 101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138
Episodes 4142434445464748495051525354
The Truth of the Petrification Saga
New America City Arc
Chapters 139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169
Episodes 555657
South America Arc
Chapters 170171172173174175176177178179180181182183184185186187188189190191192193
New Stone World Arc
Chapters 194195196197198199200
Globetrotting Arc
Chapters 201202203204205206207208209210211212
Stone to Space Saga
Moon Mission Arc
Chapters 213214215216217218219220221222223224225226227228229230231232