Ruri Rocks (瑠璃の宝石, Ruri no Houseki, meaning "Ruri's Jewels"), also known as Introduction to Mineralogy, is a manga by Keiichirō Shibuya that began serialization on August 10, 2019, in Enterbrain's Harta Magazine. It has an anime adaptation by Studio Bind that began airing in the Summer of 2025. Crunchyroll has licensed the anime, and it can be viewed worldwide except in Southeast Asia (where it is licensed by Plus Media Networks Asia).
High schooler Ruri Tanigawa thought that jewels and minerals were so exotic that they could never be found en masse in Japan. Upon realizing the opposite, her desire to acquire these sparkly rocks had her cross paths with geological graduate student Nagi Arato; together, their love of the land and its output will only soar.
Tropes:
- Adaptational Curves: Ruri's mother and especially Yoko have more prominent bustlines in the anime than in the manga. While Nagi and Aoi were already busty in the manga, the anime gives them even larger busts too.
- Adaptation Expansion: In the anime episode that introduces Shoko, her backstory is considerably expanded to show how she was bullied as a child for being interested in rocks, and her parents thought she can't make a career out of it.
- Adaptation-Induced Plot Hole: In the last episode of the anime, Yoko bringing the microscopes with them when they're on vacation at a hot spring looks like a weird example of her being Crazy-Prepared. (She won the hot spring reservation in a lottery in The Stinger of the previous episode.) However, in the original manga, they weren't on vacation; that chapter was the third part of the story arc where they go on an expedition to hunt for topaz, and the microscopes were part of their equipment.
- Adapted Out: The scene in Chapter 2 where Ruri gets a Male Gaze of her butt from an unnamed male shop clerk (when she's trying to show off the new rock hammer she's wearing on her belt) is skipped in the anime.
- Alliterative Title: Ruri Rocks.
- All-Natural Gem Polish: Downplayed — the gemstones they discover aren't cut, and the process of polishing stones is shown onscreen, but the protagonists regularly find huge deposits of improbably clear, sparkly, gem-quality minerals, like the pool full of garnets, the piles of opals discharged from a dam, and the vein of sapphire in the side of a cliff that used to be worshipped as a blue dragon god. Nagi usually provides exposition about just how improbable a set of circumstances has to come together to allow these deposits to be formed.
- Ambiguous Situation: It isn't clear how much time passes between the rockhounding trips. It's implied that the characters only go rockhounding on weekends, and the high school students change from winter to summer uniforms over the course of the anime. We also aren't shown how much Ruri and Shoko have told their parents about their mineralogy activities, or whether they've introduced Nagi and Yoko to their parents.
- Art Shift: The art style changes into chibi when Nagi is delivering exposition, and uses an ukiyo-e style when elaborating on Japan's pre-industrial mythology.
- Bland-Name Product: Nagi's car is obviously a Mini Cooper, but the Mini logo is never clearly visible and the badge says "Color S". A "Stonebucs" coffee shop appears in episode 12 of the anime.
- Bust-Contrast Duo:
- The flatter, shorter, and energetic Ruri against the bustier, taller, and cool-headed Nagi.
- This is also the case when Ruri is paired with Shoko, who is completely flat with a subdued personality.
- California University: Nagi and Yoko attend "Maeshiba University", which is a stand-in for Gunma University in Maebashi, the capital of Gunma Prefecture. In real life, Maeshiba is a district of Toyohashi, which is over 350 km away from Maebashi. Curiously, in the manga the paper Nagi wrote is entitled "Pyrite in the North Gunma Mining Area", but the anime removes "Gunma" from the title in order to enforce Where the Hell Is Springfield?
- The Cameo: In addition to the Adaptational Early Appearance of Natsuki Sasaya at the hardware store in episode 12, the other people inside and outside the coffee shop are also main characters from Daikagaku Shoujo.
- Character Development:
- Ruri eventually stops being a Spoiled Brat and gains professional mineral-hunting skills. She comes to value minerals in order to understand how they were formed and transported to their present locations, instead of just on an aesthetic level.
- Shoko becomes less of a Shrinking Violet, having found people she can talk to about her love of rocks and being assured that she can pursue it as a career.
- Yoko has more confidence in her practical mineralogy abilities after doing more fieldwork.
- More subtly, Nagi's relationship with Ruri makes her realize that her true desire is teaching, and she turns down an offer for a position as a museum curator in order to aspire to become a professor of mineralogy.
- Chromosome Casting: All of the main characters are female. The anime only has male characters in small roles like Shoko's father, the head priest of the Suou Shrine, and the Blue Dragon God in the recounting of his legend. In the manga, it doesn't become apparent that Ruri's school is co-ed until the introduction of the Chemistry Club, which has only one male member.
- Creator Thumbprint:
- In the manga, Ruri looks identical to Kaya-chan, the protagonist of From Now on, Together with Senpai, the yuri hentai doujinshi series that Shibuya drew under his pen name "Soso-Zagri".
- The anime modifies Ruri's character design with more prominent bangs, making her resemble a genderswapped version of Rudeus, the protagonist of Mushoku Tensei: Jobless Reincarnation, previously adapted by Studio Bind.
- Diegetic Soundtrack Usage: When Ruri finally gets her crystal radio working in the anime-exclusive episode 12, the song she hears in the earpiece is "Hikari no Sumika", the anime's opening theme.
- Distant Finale: The final shot of the anime depicts an older, stronger, well-equipped Ruri triumphantly standing before her latest discovery.
- Edutainment: The series pays equal attention to the information about geology and mineralogy that the characters exposit as it does to the adventures they go on.
- First-Name Basis: Nagi initially calls Ruri "Ruri-chan", but by the time of their second rockhunting trip, Ruri tells her she can drop the honorific with her because they're friends. Ruri continues to call Nagi "Nagi-san".
- Freeze-Frame Bonus:
- In the anime's opening sequence, Ruri finds something shiny in a river and looks enthusiastic at first, then gives it an angry glare and throws it away. It seems to be the marble from a Ramune bottle.
- When Nagi shows Ruri the paper she wrote about pyrite, only the title and byline in both Japanese and English are clearly visible. The rest of the text is blurred, but close examination shows it to be the English Wikipedia article on pyrite.
- Fun T-Shirt: In later episodes of the anime, Ruri starts wearing a T-shirt that says "SiO₂", the chemical formula for quartz, and Shoko wears a hoodie reading "Nh 113" for element 113, nihonium. It also says "Uut" on the sleeve, which stands for ununtrium, the temporary name for element 113 before it was discovered. In the manga, Shoko also has a nitrogen-related shirt that says "Stickstoff" (the German word for nitrogen) on the back.
- Girly Girl with a Tomboy Streak: The characters all fall on different parts of the girly-tomboy spectrum, but of necessity, they have to wear rugged outdoor clothes on rockhounding trips. Ruri is the most feminine character, and it takes her a considerable amount of time to realize she shouldn't wear skirts to go hiking. Nagi always wears clothes that are generally masculine-looking but fit tightly, and she also has the longest hair in the cast and is the only one who always wears earrings. Shoko wears a lot of androgynous casual clothes outside of school, but she becomes very interested in the "cute outfits" that Yoko brought for Nagi to try on. And while Yoko has very short hair, she's neither boyish nor authoritative, frequently wearing long skirts and an apron in the lab.
- Good-Times Montage: The end credits of episode 7 play over a montage of Ruri and Shoko becoming friends. The credits of the final episode show Aoi joining the team and Ruri and Nagi taking Yoko, Shoko and Aoi to the mineral sites that they previously visited by themselves.
- Hair Flip: Ruri does an arrogant hair flip when she boasts to Aoi that she can easily get her mother to buy her a crystal (only to be Instantly Proven Wrong).
- Hot Springs Episode: The girls stay at a hot spring in chapter 20 of the manga and episode 13 (the finale) of the anime. The TV airing had a lot of Censor Steam, but this is reduced in the Blu-ray release to reveal only Barbie Doll Anatomy.
- Informed Attribute: When Ruri and Shoko polish opals with a grinding stone, they're impressed that they come out looking like the opals found in stores, but because of All-Natural Gem Polish, the opals don't look any different to the audience.
- Instantly Proven Wrong:
- The first scene involves Ruri getting charmed by a crystal at a store and boasting to her friend Aoi that she can get her mother to buy it for her easily. The scene then Smash Cuts to her pathetically begging her mother for an allowance, which is quickly refused.
- In a more heartwarming example from the first episode, Ruri hits her head after the long, tiring hike and complains "I should've just bought my crystals at the store. Even if I found one now, I wouldn't be happy at all," but when Nagi shows her a crystal she's instantly mollified.
- Last-Name Basis: Everybody calls Yoko and Shoko by their last names, and Shoko calls everybody by their last names.
- Male Gaze: Nagi is a very attractive woman with a nice bust and rear, and the camera frequently emphasizes those.
- Meaningful Name: As Nagi notes, Shoko's name is written with the kanji for glass, and Ruri is an old word for blue glass. (Ruri is also more commonly the Japanese word for lapis lazuli.)
- Minimalist Cast: The cast is made of only a handful of characters, with other people rarely being seen on-screen and even more rarely having a speaking role.
- The Oner: This promo video
for the anime, which doesn't appear in the anime itself, is a one-minute-long shot that continuously pans over beautiful forest backgrounds demonstrating Studio Bind's commitment to Scenery Porn. - Percussive Therapy: Ruri gets so angry that she and Nagi are forbidden from searching an area that she tries kicking the warning sign, but is stopped by Nagi, who gets curt with her for the first time and tells her to behave.
- Product Placement: In the anime, the characters use Estwing rock hammers and the geology lab has several Olympus microscopes.
- Scenery Porn: The anime prominently features very detailed backgrounds where the characters hike through gorgeous forest environments, rivers, waterfalls, rock formations, and establishing shots of Ghibli Hills.
- Science Hero: This is one of the rare manga and anime where the protagonists are purely observational scientists rather than engineers or inventors. Nagi speaks at length about why she chose mineralogy as her field of study and why she considers it to be important.
- Tourist Bump: In-Universe. During the manga's story arc about the topaz expedition that extends past the ending of the anime, the team is dismayed to learn that the topaz-bearing river was featured in a TV show the previous month, leading to crowds of people showing up looking for topaz which has now been practically picked clean. However, by deducing how the river had changed its course in the past, they successfully find topaz by digging in a construction site with the workers' permission.
- Trash of the Titans: Nagi and Yoko's office is an accurate depiction of a researcher's office in a slightly old-fashioned university: a carefully-balanced mess of books, rock samples, tools, more books, toys someone brought in and forgot about, fading posters, and even more books, with just enough space kept clear for a microscope or laptop. The chapter 5/episode 3 footnotes feature an annotated diagram of Nagi's desk, and Yoko explains why it's important for mineralogists to keep old books around.