Bofoi/Synopsis

History
Sometime prior to the original storyline, Child Emperor worked as Metal Knight's assistant.

Giant Meteor Arc
Bofoi arrives just as Genos prepares to take on the giant meteor and Genos recognizes Bofoi. Genos introduces himself and asks Bofoi for his help, but Bofoi refuses, stating that he is only there to test out a new weapon, and that he would prefer to be called Metal Knight, as it is courtesy to call a hero by his real name. He then reveals that he isn't even in Z-City, but is instead using a remote-controlled robot from a safe distance away. As Genos then runs off to a better place to stop the meteor, Bofoi fires a volley of large missiles that converge on the meteor and cause a massive explosion. This, unfortunately, is not enough to stop the meteor which bursts through the cloud of smoke caused by the explosion much to both Genos and Bofoi's surprise.

Alien Conquerors Arc
After Boros's defeat and the fall of the Dark Matter Thieves' spaceship, Bofoi, through one of his robots, appears in the ruins of A-City to collect the remains of the spaceship. Genos then confronts him asking what he will do with it, and Bofoi answers that he will use their technology to make new powerful weapons, that are needed for the sake of peace. It is also revealed that Genos and Bofoi may have a connection, as Drive Knight tells Genos that Bofoi is his "enemy". At some point after the invasion, he took Boros's ship and is now trying to develop new technology.

Monster Raid Arc
While Elder Centipede wrecks havoc to S-City, Bofoi arrives and attacks Elder Centipede. Despite his powerful set of missiles, Elder Centipede only gets annoyed. Bofoi see this as an opportunity to collect Elder Centipede skin after his defeat to build more weapons. He then tells the Mohican and Pineapple to leave because of the potential destruction his weapons can cause.

After successfully capturing the child of a sponsor, Elder Centipede took Phoenix Man and Rhino Wrestler and proceeded to retreat underground. Shocked by Elder Centipede's retreat, Metal Knight gave chase, persistent not to lose his target. He successfully grabbed onto Elder Centipede as they disappeared underground.

Super Fight Arc
At some point, Bofoi's robot was severely damaged by Orochi and was captured at Monster Association's Headquarter, and its broken pieces are hung in chains.

Despite the damage, it is still operational and is apparently being used by Bofoi to spy on Orochi and Gyoro Gyoro. Through his robot Bofoi questions Orochi and Gyoro Gyoro about their goals and while they tell him destruction is a natural part of a monster's instincts, it is not their end goal.

Monster Association Arc
Bofoi is discussing with Child Emperor and tells him that he will not join in on the operation to raid the Monster Association. He tells Child Emperor that the Monster Association is thoroughly prepared for the Hero Association and that many heroes will be sacrificed in the process. Bofoi tells him that the Hero Association denied permission for him to plant explosives in the designated hideout of the Monster Association headquarters because saving the hostage was their highest priority. Due to this, Bofoi will not bother with the operation. Child Emperor continues tries to convince Bofoi to partake in the raid but is rejected by Bofoi, who refuses to participate due to other potential threats. Bofoi mentions how Monster King Orochi pierced through the Metal Knight drone before it could activate its self-destruction mechanism. Bofoi suggests to Child Emperor to not trust those around him and to accumulate his power as you only need yourself to fight for justice. As a result, Child Emperor tells Sekingar to take Demon Cyborg off the roster due to a suspicious history and Silver Fang due to his past relationship with Garou.

The Metal Knight drone that was rendered inactive by Orochi is reconstructed unsuccessfully.

Psychic Sisters Arc
After Caped Baldy makes his way into the A Rank of the Hero association. Dr. Bofoi takes an interest in him after a security system installed for the new HQ he had constructed using the invaders ship, was dismantled by the former single handed.

While looking over the video surveillance Bofoi decides to study Saitama's superhero registration entry. Looking into his hero activity he finds nothing of interest other than his sharp rise in the ranks over the course of three months, yet notices, while viewing the security footage, that the defense robots he designed were made to take down Demon level threats; and for him to have so easily taken them apart implicates his power being either at or greater than S class.

Fall of the Hero Association Arc
After the fiasco concerning Fubuki, Tatsumaki and Caped Baldy resulted in the destruction of the new superhero base and the escape of all the Mysterious Beings incarcerated in its basement. Bofoi gains a grudge against Saitama after the incident he caused had unintentionally ruined Bofoi's reputation with his contractors.