Kaseki (カセキ) is the artisan of Ishigami Village. With expert skill and precision formed by his numerous years of experience as a craftsman, he is a key member of the Kingdom of Science, responsible for creating many of their scientific inventions.
Kaseki is a bald, short, old man with a large, white beard. Although initially appearing to be frail, when fired up, he bursts through his clothes, revealing a muscular body, likely honed by his years working as a craftsman.
Kaseki is an honest older man who is prideful in his work and skill as an artisan. Unassuming unless provoked, he displays boundless energy when excited about his work.
Originally wary of Senku, Kaseki quickly becomes a loyal and prominent member of the Kingdom of Science. His love for crafting since his childhood helps him form strong bonds with advocates of science. Having been relatively isolated for much of his life due to his interests, he now considers Senku and Chrome as close friends, despite their age differences. He is alike to them in the fact Kaseki is passionate about his craft and despairs when it fails.
A genius craftsman, Kaseki picks up techniques with little effort. Upon seeing glass for the first time, he immediately understood how to work best with the material.
As one of the oldest members of the Kingdom of Science, Kaseki is relatively wise. He often imparts wisdom on the other members, and is unafraid to admit his own shortcomings.
Despite his pride, Kaseki often seeks external validation for his work, particularly from women.
Abilities and Skills
- Master Artisan: Kaseki is a master artisan with over fifty years of experience. He designed and built much of Ishigami Village, including the island's bridges. He also made Kohaku's shield, originally for her father Kokuyo as a reward for winning the village tournament and becoming chieftain. Kaseki picks up new techniques extremely quickly, inherently understanding how to use materials he's never seen before. He can craft objects solely from Senku's diagrams with little practice. He's even able to create extremely complex structures, including engines and vacuum tubes. Senku admits that Kaseki's skills far surpass his own.
- Intelligence: Along with Chrome, Kaseki is one of the original two members of Ishigami Village with scientific knowledge. He's shown to be extremely knowledgeable, particularly about crafting techniques.
- Physical Abilities: Kaseki's physical abilities are high, despite his old age, due to his physically-demanding work, and they were further heightened after Kaseki was revived thanks to the healing properties of the petrifaction process. He is strong enough to tear through ropes. However, he has limited combat experience.
- His name, Kaseki, is the Japanese word for fossil.
- This seems to be a joke about his age.
- Kaseki has a habit of ripping apart his clothes when he gets excited, even while wearing difficult-to-produce clothing crafted by Yuzuriha.
- He ranked 9th in the 1st popularity poll and 14th in the second poll.
- Kaseki appears to be particularly fond of their vehicles, as he is shown distraught when they give the first car an upgrade  and after they repurposed parts of the mobile lab. 
|Male||Alabaster • Argo • Carbo • Chrome • Ganen • Genbu • Ginro • Hagane • Jasper • Kaseki • Kinro • Kokuyo • Magma • Mantle • Natri • Sagan • Sho • Soyuz • Tetsuken • Titan • Unmo|
|Female||Alumi • Azura • Beryl • Dia • En • Garnet • Kohaku • Kujaku • Namari • Ruby • Ruri • Sango • Sapphire • Shirogane • Shovel • Suika • Suzu • Turquoise|
|Unknown||Chalk • Sagara|
|Male||Chrome • Gen Asagiri • Ginro • Hyoga • Kaseki • Kinro • Kokuyo • Magma • Matsukaze • Mozu • Ryusui Nanami • Senku Ishigami • Taiju Oki • Tsukasa Shishio • Yo Uei|
|Female||Homura Momiji • Kirisame • Kohaku • Minami Hokutozai • Nikki Hanada • Ruri • Suika • Yuzuriha Ogawa|
|Alabaster • Argo • Carbo • Chrome • Ganen • Genbu • Ginro • Hagane • Jasper • Kaseki • Kinro • Kokuyo • Magma • Mantle • Natri • Sagan • Sho • Tetsuken • Titan • Unmo|
|Alumi • Azura • Beryl • Dia • En • Garnet • Kohaku • Kujaku • Namari • Ruby • Ruri • Sango • Sapphire • Shirogane • Shovel • Suika • Suzu • Turquoise|
|Soyuz's father • Ibara • Matsukaze • Mozu • Oarashi • Soyuz|
|Amaryllis • Kirisame|