SERVBOT or Search then Eradicate Radical Vagabonds By either Obliteration or Torture is the Security Drones of the Mephisto Brotherhood.
In Japanese, they are called Unit 494 or Shinumade Kurushimu, an infamous phrase meaning "slow and painful death."
The SERVBOT bears great resemblance to the Agonizer except that the former is fully-customizable and can be piloted.
Mizuhiro Mikado stole one of the SERVBOTs then reprogrammed and customized it to be his own servant. He affectionately named his SERVBOT as Pyron which means Fire (similar to Hydron that means Water).
Mizuhiro mentioned Pyron to have been downgraded from a weapon of destruction into a simple housekeeping robot that does household chores and gardening. Mizuhiro won't be able to do all the chores either because he's busy with his job in the Grammaton or he's simply being a lazy brat prince like before.
Pyron was also nicknamed Maidbot by Mizuhiro's neighbors because the former SERVBOT is wearing a pink apron.