Ken Ishiyama

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

Appearance
Cementoss appears to be a humanoid block of cement.

Personality
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 Shouto, noting that Izuku's injuries were serious and wanted to stop the match for Izuku's sake.

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

Sports Festival Arc
Cementross is seen creating the ring for the tournament event, which Present Mic thanks him for. After he creates the cement ring, Cementross 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 Shouto, 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 Shouto launch their final attack, Cementoss decides to intervene by creating cement pillars between Izuku and Shouto to try and stop them. However, Izuku's and Shouto'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.

Quirk
"Cement" - Cementoss's Quirk allows him to manipulate cement material that he touches, really useful in a city environment. In contrast, it's not really useful in other places in nature.

All Might
He loves meeting All Might all the time.

Trivia

 * "Ken" (堅) 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.