"Listen. When it comes to fighting... It's all about making use of your particular strengths."

Ken Ishiyama to Eijiro Kirishima and Rikido Sato in "Stripping the Varnish"

Ken Ishiyama (石山堅 Ishiyama Ken?) also known as Cementoss (セメントス Sementosu?) is a Pro Hero and one of the staff at U.A.. He teaches Modern Literature.


Cementoss appears to be a humanoid block of cement. His body shape is evenly blocky all around his body. His eyes are generally closed and his lips are pulled upwards. His hero costume consists of a sleeveless black shirt with collar and black shorts along with a belt.


Cementoss can be serious when its necessary and can quickly change to a happy fan. Cementoss cares about the well-being and health of his students, trying to stop the match between Izuku and Shoto, noting that Izuku's injuries were serious and wanted to stop the match for Izuku's sake.


Unforeseen Simulation Joint Arc

At the end of the arc, he appears with alongside the other Pro Heroes. When Eijiro Kirishima runs over to see if All Might was okay, he uses his Quirk Cement to create a long cement wall to stop him from seeing All Might's true form.

Sports Festival Arc


Cementoss as the final proctor of the Sports Festival.

Cementoss is seen creating the ring for the tournament event, which Present Mic thanks him for. After he creates the cement ring, Cementoss makes a cement chair for himself to sit on so he can act as the proctor for the tournament event.

During the fight between Izuku and Shoto, Cementoss contacts Midnight and asks her if he can stop their fight, saying that Izuku's injuries are serious and that even Recovery Girl won't be able to heal his injuries fully in a single session, noting that if Izuku was able to even win he wouldn't be able to fight properly in the next match. As Izuku and Shoto launch their final attack, Cementoss decides to intervene by creating cement pillars between Izuku and Shoto to try and stop them. However, Izuku's and Shoto's attacks hit Cementoss's cement pillars, destroying them and, as a result, creates a huge shock wave. After the shock wave subsides, Cementoss says that while the force of their attacks was not a good thing, he notes that the power was incredible.

Field Training Arc

In the faculty room, Cementoss informs All Might that a new nomination has arrived and the nomination is for Izuku.[1]

End of Term Test Arc

On the day of Class 1-A's test exercise, Cementoss is one of the teachers that Class 1-A will face in their end of term test exercise.[2] Cementoss will face Eijiro and Rikido in their test exercise.

Rikido, Eijiro and Cementoss arrive in an uninhabited city where their test exercise will take place. Cementoss explains the 30 minute test; Rikido and Eijiro must either handcuff him or one of them must escape the battlefield within 30 minutes in order to win and pass the test. The test begins.[3]

Eijiro and Rikido keep smashing their way through Cementoss' cement walls, but the more walls they destroy, the more walls Cementoss keeps creating to keep them at bay. Cementoss tells Eijiro and Rikido that their weakness is drawn out battles and advises the duo to push their strength to the limit. Eijiro and Rikido are unable to get past Cementoss' walls by the time the End of Term Test finishes and as a result, they fail.[4]

Hero License Exam Arc

Cementoss along with All Might, Ectoplasm and Midnight, were the repossessed by training class A and B students to develop their Quirks and special techniques before the provisional hero license test.

Quirk and Abilities

Cement (セメント Semento): Cementoss' Quirk allows him to manipulate cement material that he touches, allowing him to shape it into various forms.

3/5 C
2/5 D
5/5 A
5/5 A
4/5 B
Ken's stats, according to the Official Character Book


End of Term Test Arc


All Might

He is a fan of All Might and was so happy when he met him for the first time.


  • "Ken" (?) means "stiff, firm, hard". "Ishiyama" (石山?) means "Stone Mountain". "Cementoss" is possibly a combination of "cement" and "toss".
  • According to Volume 4:
    • He's a big fan of All Might.
    • He likes round things (whilst being, ironically, blocky).
    • His favorite food is manju.
    • On his profile in volume 4, the author commented that he should have given Ken's hair a crew cut.



  1. Boku no Hero Academia Manga: Chapter 45
  2. Boku no Hero Academia Manga: Chapter 60
  3. Boku no Hero Academia Manga: Chapter 61
  4. Boku no Hero Academia Manga: Chapter 67
  5. Boku no Hero Academia Manga: Chapter 67, Page 2

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U.A. High
Class 1-A Students Denki KaminariEijiro KirishimaFumikage TokoyamiHanta SeroIzuku MidoriyaKatsuki BakugoKoji KodaKyoka JiroMashirao OjiroMezo ShojiMina AshidoMinoru MinetaMomo YaoyorozuOchaco UrarakaRikido SatoShoto TodorokiTenya IidaToru HagakureTsuyu AsuiYuga Aoyama
Class 1-B Students Hiryu RinIbara ShiozakiItsuka KendoJuzo HonenukiJurota ShishidaKinoko KomoriKojiro BondoKosei TsuburabaManga FukidashiNeito MonomaNirengeki ShoudaPony TsunotoriReiko YanagiSen KaibaraSetsuna TokageShihai KuroiroTetsutetsu TetsutetsuTogaru KamakiriYosetsu AwaseYui Kodai
Department of Support Mei Hatsume
General Department Hitoshi Shinso
Third Year Students Mirio TogataNejire HadoTamaki Amajiki
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Locations Class 1-AClass 1-BDevelopment StudioGround BetaGround GammaGym GammaHeights AllianceLunch Rush CafeteriaRecovery Girl's Nurse's OfficeSports Festival StadiumUnforeseen Simulation Joint
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Related Articles CostumeHero NameHero OfficeQuirkU.A. High

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