|— Building Booper
Building Booper was a lean detonator with arms, legs, a long electric cable as a tail, and a predatory face with one eye. The bottom of his detonator body is striped in black.
Building Booper appeared to be a sadistic monster. He destroyed buildings around him to block the escape route of the heroes who had raided the Monster Association Headquarters, stating that they would die to Orochi's tentacles.
Building Booper is seen in Z-City blocking the heroes' escape and supply routes on the surface by causing several buildings around the routes to collapse with explosives. He presumably dies when the combined strength of Saitama, Waganma, Child Emperor and Underdog Man push the exit manhole below the two collapsed buildings, where he is standing, sending all him and the buildings flying in the air and eventually falling to the ground which seems to result in his death.
Abilities and Powers
As a Demon-level Mysterious Being, Building Booper was likely a fairly powerful monster. He had the ability to cause buildings to collapse by blowing them up with explosives.