Chen Yu

Biodata

Background / History

Original Life and Rebirth

Chen Yu’s original life was dominated by illness, pain, and hospital stays. Before dying, he wished for a healthy body and a clever mind so that he could study medicine and save people suffering as he had. He was subsequently reborn as the only child of a wealthy family, retaining memories of his previous life 1 2.

His medical education began unusually early: he read medical and pharmaceutical books at three, exercised and wrote simple herbal prescriptions at seven, and received a teacher and additional tutoring at ten. He also enrolled in martial arts classes. Concerned that he rarely left home except for school and training, his parents took him to Japan under the pretext of a business trip 1.

Meeting Tsukasa and Senku

During the trip, Chen Yu intervened when a man attacked Tsukasa Shishio for collecting seashells. After learning about Tsukasa’s sick younger sister, he helped locate her hospital and persuaded his parents to fund her treatment. Recognizing Tsukasa from his previous-life memories, he realized that he had entered the world of petrification 2.

Over the following years, Chen Yu published effective medical research and became internationally known as a young medical expert. He continued paying Tsukasa’s sister’s monthly treatment costs, while hoping that his reputation would give others a reason to revive him after humanity’s petrification 2 3.

He deliberately transferred to Senku’s school in Japan. Their early friendship involved Chen Yu repeatedly testing medicines on Senku in an attempt to curb his dangerous obsession with science; Senku instead developed drug resistance. Japanese authorities later pressured Chen Yu to remain, but intervention from his home country ended their efforts 3.

Petrification and Early Revival

Chen Yu anticipated the petrification event, left Senku and Taiju shortly before the green light arrived, and messaged Tsukasa. Inside his stone body, he remained conscious for an extended period by replaying memories and reviewing his knowledge, eventually drifting into sleep. Approximately 3,700 years later, he revived beside Senku, Taiju, and Tsukasa 4.

Although Senku suspected that his departure indicated foreknowledge, Chen Yu denied knowing the cause of petrification. He acknowledged that he was Senku’s ally but initially refused to fight either Senku or Tsukasa, hoping to reconcile his two friends instead 4 5 6.

He advised Senku’s group to make Tsukasa believe Senku was dead, then collapsed after swallowing herbs as Tsukasa arrived. Later, he led Tsukasa away from the laboratory so Senku, Taiju, and Yuzuriha could retrieve supplies, while openly betting that Senku’s ideals were right 6 8.

Medical Work and Cooperation with Ishigami Village

Chen Yu helped prepare revival fluid and taught Tsukasa’s settlers hunting, butchery, and injury treatment. His painful punishments for troublesome settlers earned him a frightening reputation that also affected Taiju and Yuzuriha 9 11 21.

After accompanying Gen to Ishigami Village, he supported Senku’s work and demonstrated his martial skill by defeating Kohaku. When Magma ambushed Gen, Chen Yu intercepted him and presented the incident as an attack on himself. His confrontation with Kokuyo secured cooperation for Senku’s group and custody of Magma and his accomplice 12 13 18 19.

Back in the Tsukasa Empire, he established a Medical Team with Reiko, Miwa, and Xiao Xi. He began treating Xiao Xi’s speech condition and punished a man who sexually harassed her. He later secured Reiko and Miwa’s willingness to assist his secret plan to restore civilization 23 25.

A New Purpose in the Stone World

Chen Yu questioned why he had been revived and whether his medical knowledge truly gave him a purpose. Senku explained that he had hoped Chen Yu could identify the petrification’s cause and, failing that, act as a go-between with Tsukasa. He then proposed using Chen Yu’s pharmacology offensively and named him leader of the Biochemical Weapons Action Team 34.

Chen Yu accepted medicinal powders as a foundation for supporting Senku against future obstacles. He also explained to Tsukasa that traditional Chinese medicine was his priority because it would be easier to pass down in the Stone World; Tsukasa resolved to help preserve it 34 35.

Encounter Across Millennia

While preparing a prescription, Chen Yu saw a light and unexpectedly appeared aboard Earth’s space station during the petrification event. He told Byakuya Ishigami and the other astronauts that he came from 3,700 years in the future, described their descendants, and reassured Byakuya that Senku was doing well 39.

At his request, Lillian sang a song that he memorized. After he disappeared, everyone except Byakuya forgot the encounter, and Byakuya wrote it down to preserve his memory. Chen Yu returned to his own time intending to sing Lillian’s song for future generations. Ruri’s inherited knowledge already included both his name and Senku’s 38 39.

Exposure as Senku’s Ally

During a visit to Ishigami Village to commemorate his homeland, Chen Yu learned of Hyoga’s earlier attack and continued training the village’s fighters. When another attack came, he captured the Pink-Haired Girl before she could start a fire and prevented Hyoga from taking his spear 44 45 46.

Hyoga subsequently branded Chen Yu a traitor, but Tsukasa refused to act against the doctors. Chen Yu remained with Senku’s group because his exposure prevented his return as a covert ally. He expected the conflict’s eventual resolution to let him return not as an outsider, but as someone “coming home” 46 47.

Appearance

• Appears to Gen as an ordinary teenage boy before demonstrating his fighting ability 13.
• Described as handsome by a watching village girl during his match with Kohaku 13.
• Carries visible petrification cracks, which villagers recognize as resembling Senku’s 13.
• Frequently keeps small tools or weapons concealed in his sleeves and later carries a sword case on his back 13 16 31.

Personality

Chen Yu treasures his healthy second life and considers survival more important than achievement. His childhood was quiet and studious to the point of worrying his parents: he preferred reading at home to travel or socializing. His experience of dying also explains his concern that Senku’s relentless research could endanger him 1 2 3.

He is deeply loyal to his friends, refusing to attack either Senku or Tsukasa despite understanding their incompatible ideals. He repeatedly describes himself as medical support rather than a fighter and dislikes war because it rapidly harms and kills people 6 17 31.

His reluctance to wage war does not prevent harsh treatment of individuals. He uses intimidation, painful acupuncture, and exhausting training against bullies, harassers, and uncooperative allies. His poison prank frightened Gen, while his unauthorized drug experiments angered Senku 11 14 23 33 47.

Preserving his homeland’s medical traditions is a personal commitment. He became a prominent advocate for Chinese herbal medicine before petrification and later commemorated his homeland by drawing an image on the ground and saluting west 35 43 44.

Abilities & Skills

Exceptional Memory and Learning

Chen Yu’s unusually capable mind allows him to retain and apply enormous amounts of information. Senku compares it to a human computer 4 43.

• Memorizes medicines, their effects, preparation methods, and prescription compatibility 1 43.
• Replays detailed memories during petrification, including images from programs he previously watched 4.
• Masters medical knowledge at an accelerated pace; Senku credits him with storing the relevant knowledge and developing new applications in eight years 14.
• Retains incomplete knowledge of the story from his previous life. His recollection of particular people and events depends partly on his condition when he originally encountered them 8 20.
• Memorizes Lillian’s song during his encounter with the astronauts 39.

Medicine and Pharmacology

Traditional Chinese medicine is Chen Yu’s principal specialty, supported by pharmaceutical research and knowledge of modern medicine 2 29.

• Herbal identification and prescriptions: Recognizes medicinal ingredients, dangerous interactions, and look-alike plants such as pokeweed and ginseng 1 24.
• Suspended Thread Pulse Diagnosis: Uses a thread attached to a patient’s wrist to assess their condition; diagnoses strain in Senku’s lungs and muscles 13.
• Patient care: Treats wounds, prepares ointments, monitors exhaustion, and oversees Xiao Xi’s speech treatment and recovery 4 16 23 35.
• Precise dosage: Can judge the weight of herbs by touch without a scale, according to Senku 43.
• Medical instruction: Trains assistants, organizes herbs, and teaches settlers injury treatment 11 23 35.
• Limits: Specialized instruments and sufficient needles are necessary for some techniques. He acknowledges that mental conditions can be difficult to treat and cannot simply reverse petrification through acupuncture 13 32 34.

Acupuncture

Chen Yu uses acupuncture for healing, restraint, and coercion. His self-developed techniques combine ancient texts with modern medical knowledge 29.

Martial Arts and Internal Energy

Chen Yu studied numerous forms of kung fu, including unarmed combat, spear techniques, and swordsmanship. Despite repeatedly minimizing his combat role, he defeats Kohaku and overwhelms Magma 13 19 30 31.

• Tai Chi: Dissipates and redirects an opponent’s force; defeats Kohaku without initiating attacks during their first match 13.
• Tube Spear Style: Demonstrates an approximation of Hyoga’s technique. His version is faster, but he admits to having only recently picked up part of it 30.
• Return Horse Spear: Uses an unexpected backward counterattack against a pursuing opponent; Kinro later applies the move against Hyoga 30 44.
• Swordsmanship and footwork: Performs an acrobatic sword routine and rapidly closes distance to restrain Miwa 27 31.
• Internal energy: Assists movement, propels a concealed pebble, and supports acupuncture techniques 9 15 23 32.
• Danger sense: Detects the Pink-Haired Girl’s attempted arson despite her agility and stealth 46.

Limits and comparative strength:

• The author places Tsukasa above Chen Yu under ordinary circumstances, while stating that an enraged Chen Yu can defeat him; his upper limit remains unspecified 28.
• Training in too many conflicting styles caused muscular and tendon problems, joint dislocations, and a period of recovery. He never fully integrated everything he learned before petrification 31.
• His combat effectiveness is reduced without specialized tools 13.

Poisons and Medicinal Powders

Chen Yu’s pharmacological expertise includes substances intended to incapacitate opponents, as well as an exceptionally dangerous poison developed before petrification 7 33 34.

• Paralysis Powder: Processes poisonous gelsemium into a powder that causes Senku to lose sensation and sleep until evening 33.
• Pre-petrification poison: Creates a fingernail-sized pill capable of poisoning water merely through contact. Fearing its loss, he has it encased in a special material and sealed inside concrete 7.
• Unintended ecological disaster: Weathering eventually exposes the sealed poison. A creature consumes it, and subsequent predation spreads the contamination, causing a mass extinction in the island’s northern region; recovery takes several hundred years 7.
• Proposed delivery methods: Considers shattered glass bottles, favorable winds, and small explosive charges as ways to disperse medicinal powders. These are plans rather than demonstrated weapons 35.

Craftsmanship and Survival Skills

• Wood and miniature carving: Practices increasingly fine carving, eventually working on grains of rice; this develops exact control over cutting pressure 50.
• Small mechanisms: Builds a sleeve-mounted arrow launcher from available materials 16.
• Papermaking: Collaborates with Kaseki to produce paper successfully 48.
• Survival instruction: Butchers and cleans animals and teaches settlers which parts can be eaten 9 11.
• Camouflage: Conceals his sword equipment at a location known only to him 32.
• Crafting limits: Abandons an attempted mold when he realizes that he lacks the skills to make it properly, leaving more difficult work to Kaseki and Yuzuriha 34.

Equipment / Weapons / Items

• Acupuncture needles — Uses bone needles made by Yuzuriha and later works with Kaseki and Kohaku to produce seven iron needles and two silver needles. Bone needles are thicker and less suitable than his preferred instruments 23 29.
• Wooden-framed folding fan — Made with animal hide by Yuzuriha; blocks Kohaku’s wooden sword and conceals his pebble-launching trick 13 15.
• Sleeve Arrow — Concealed launcher activated with a flick of the hand. Its small size and poor materials reduce its destructive power 16.
• Sword case and three swords — Crafted by Kaseki. The wooden case opens through a mechanism and uses an iron chain to support its sword-storage arrangement 31.
• Custom spear — Combines Chen Yu’s flexible wooden shaft with a spearhead forged by Kaseki 45.
• Medical bag and prepared remedies — Carries needles and supplies; prepares ointments, decoctions, and powders for treatment and future use 16 29 32 35 43.

Relationships

• Tsukasa Shishio — Close friend whose sister’s treatment Chen Yu funds. Tsukasa regards him as family and a benefactor, remains protective of him, and refuses to target his doctors even after Hyoga accuses him of betrayal 2 3 8 46.
• Senku Ishigami — School friend, research partner, and ally. Their complementary scientific and medical expertise lets them coordinate with a glance, although Chen Yu’s drug experiments frequently provoke him 3 34 43.
• Taiju Oki — Friend, former research subject, and helper. Chen Yu improves their relationship by advising him about Yuzuriha’s interests 7 11 48.
• Yuzuriha Ogawa — Friend and skilled craft collaborator who makes his fan, bone needles, and other supplies 13 21 23 35.
• Gen Asagiri — Ally whose probing questions and teasing irritate him. Chen Yu frightens him with a fake poisoning but also saves him from Magma’s ambush 11 14 16 18.
• Kohaku — Sparring partner and martial arts student. Chen Yu tailors her training toward close-quarters combat rather than his own swordsmanship 13 30 31 44.
• Kinro — Learns from Chen Yu’s spear demonstrations and later uses the Return Horse Spear against Hyoga 30 44.
• Magma — Initially an aggressor whom Chen Yu captures and punishes; later becomes a demanding close-combat training partner 18 19 46 47.
• Reiko — Medical assistant and supporter of his restoration plans. He corrects her herb-identification mistakes and treats her after toxic exposure 24 25 43.
• Miwa — Medical assistant with concealed combat training. Chen Yu restrains and interrogates her, but argues against killing her and continues working with her 25 27 29 30.
• Xiao Xi — Medical assistant and patient whose speech condition he treats. He takes particular care to protect her and monitor her recovery 23 35.
• Ukyo — Initially refuses Chen Yu’s request to protect the Medical Team, but later drives Hongye Yan away from its members 23 48.
• Kaseki — Crafting partner responsible for his sword case and swords; also collaborates with him on needles and paper 29 31 48.
• Hyoga — Attempts to recruit Chen Yu into a plan to eliminate the weak, then brands him a traitor after he protects Ishigami Village 21 46.
• Byakuya Ishigami and Lillian — Meet him during his unexplained visit to the space station. Byakuya preserves a record of the encounter, while Lillian provides the song Chen Yu carries back to the future 39.

Notable Quotes

“I studied medicine so I could stay alive. Now I have another reason: to cure your sister.” 2

“One side is my friend, and the other is my friend too. I can’t hurt either of you, and I don’t want to see you fight.” 6

“I’m just support. I handle logistics, and nothing else is my responsibility.” 31

“Once it ends, I won’t be going back—I’ll be coming home.” 47