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.
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.
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.
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.
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.
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.