Bad/Synopsis

History
Metal Bat used to be a C-Class Rank 223 hero, but after impressing the Hero Association, by slaying the monster Enamel, he moved up to S-Class. Bad became an S-Class one year ago. The association members offered to arrange anything he wishes, even weapons. Metal Bat then request a bat that never breaks and received his signature metal bat. He is then berated by his younger sister for not getting Sweet Mask's autograph.

Alien Conquerors Arc
Metal Bat attended the S-Class heroes meeting, where he openly complains on missing his younger sister's piano lesson. From there, he proceeded to fight alongside the other S-Class heroes against Melzargard. During their fight, Metal Bat was smashing the monster's flying head and managed to find and destroy a marble inside its head, killing the head. With the aid of Bang and others, they are able to destroy all the marbles inside of it and kill Melzargard.

After the fight was over, the spaceship above them begin to crash down and they escape towards the headquarters. When Sweet Mask arrives and he demands an explanation. Bad and the other heroes were met with Sweet Mask's criticism. Angered by his statements, Metal Bat threatens to start a fight with him, but before the tension can escalate, they are surprised by Metal Knight's arrival.

Monster Raid Arc
Metal Bat was tasked to protect Narinki, a VIP sponsor of the Hero Association, and his son Waganma at a Mouse Sushi restaurant in S-City. He tells Waganma to not put the dishes that he has finished back on the counter, but the child doesn't listen, much to Metal Bat's displeasure. Metal Bat soon receives a call from his sister; she asks if he can take her shopping, but declines because he of his mission. His sister starts crying and hangs up the call. After the call, Metal Bat feels a sudden shaking. Metal Bat rushes back to Narinki and finds that Junior Centipede has emerged from the ground with Venus Mantrap. Furthermore, Junior Centipede had grabbed Waganma. Before the monsters could attack, Metal Bat grabs his coat and engages in a fight with the mysterious beings.

Metal Bat has just finished his fight with Junior Centipede and Venus Mantrap. Narinki and his child Waganma are delighted and wish to celebrate. However, Junior Centipede was still alive and praises Metal Bat for his strength, but still questions Metal Bat about how high he is in the food chain. Before Metal Bat could finish Junior Centipede off, Senior Centipede erupts from the ground. Senior Centipede forces Metal Bat, Narinki, and his son out of the restaurant. Outside, Rafflesidon emerged from the ground and started releasing sleeping gas. Narinki and Waganma immediately fall unconscious. Metal Bat is left to fight two Demon-level monsters. During the battle with Senior Centipede and Rafflesidon, Metal Bat temporarily came under the control of Rafflesidon's gas. When under the influence of the gas, Senior Centipede gave Metal Bat a beating. However, Metal Bat was eventually able to power through the gases' influence by smacking his own head. After regaining control, Metal Bat proceeded to defeat Senior Centipede and Rafflesidon with one strike each. However, only after the monsters were defeated did Metal Bat remember that he had not asked for their motivations.

After the Demon-level monsters were defeated, B-Class and C-Class heroes, Pineapple and Mohican, arrive at the scene. Metal Bat asks them to bring the Narinki and Waganma to the hospital so that he could finally help his sister with her shopping bags. However, Elder Centipede emerges from the ground. The lower class heroes inform Metal Bat about the monster, stating that it previously wiped out a town and it is marked as a Dragon-level monster. Metal Bat tells the two other heroes to grab the sponsor, his child and run, while he prepares to go battle. Metal Bat intercepts Elder Centipede when the monster is charging at Pineapple and Mohican, but his attack did not manage to even leave a scratch and he is launched into a building by Elder Centipede. Metal Bat then interpreted that the monster's face is its weak point. Metal Bat jumps onto Elder Centipede while Elder Centipede is chasing after two heroes. Before Elder Centipede is able to reach the two heroes, Metal Bat unleashes an attack on Elder Centipede's head. Elder Centipede then tries to shake Metal Bat off by maneuvering around the city. Metal Bat is launched hundreds of meters across the city and encounters Garou, who proceeds to attack him. The Hero Association later tries to contact him but is unable to do so, due to the fact that Garou is fighting him. Garou is able to hold back against Metal Bat, who is now much stronger than before, due to his extensive training and is already able to see Metal Bat's attack patterns. Garou comments that he is disappointed on being unable to fight Metal Bat at his best.

Metal Bat retaliates with an attack, but Garou manages to dodge it. Garou is surprised by Metal Bat's persistence despite Metal Bat's numerous injuries, but insists that Metal Bat is at his limit. Suddenly, Metal Bat rushes to Garou with incredible speed. Garou still manages to avoid Metal Bat's attacks and attempts to counterattack, but Garou's attack are no longer able to faze Metal Bat either. Garou asks Metal Bat for the reason for this sudden increase in physical strength and Metal Bat simply explains that it's fightin' spirit. Metal Bat tells Garou to hurry up with the fight because he still needs to take care of a monster. Garou throws a manhole cover at Metal Bat, but Metal Bat hits it back with his bat. However, Garou already managed to reach Metal Bat by the time Metal Bat followed through. Garou suddenly launches a barrage of attacks at Metal Bat. Metal Bat tries to take the offensive, but none of his attacks connect. Garou continues to mock Metal Bat, asking him if he's going to persist until he dies. Metal Bat retorts by saying he'll fight until he wins and proceeds to initiate a killing move. To counter Garou's swift attack, Metal Bat uses his special move Killin' Moves: Savage Tornado. Unfortunately, Garou manages to repel the attack and launch a blow to Metal Bat's chest, leaving Metal Bat laying on the ground. Abruptly, someone shouts, "Big Brother!".

Metal Bat is about to land a powerful blow on Garou, but stops because his sister Zenko is there. Garou then punches Metal Bat, but before they could clash again, Zenko jumps right in front of Metal Bat, saying that Metal Bat made a promise not to fight while she's around. Garou gets angry, but respects their promise and leaves the fight to pursue Watchdog Man.

After Zenko explains why she's there and Metal Bat remembering about the monsters, Metal Bat tries to meet Elder Centipede again, but Zenko hits him in the back of the head and Metal Bat falls on the floor unconscious, due to his exhaustion.

Super Fight Arc
An unconscious Metal Bat is later seen being taken to the hospital with Zenko watching in worry.

Monster Association Arc
When he wakes up, he is seen watching the news about the Monster Association with Zenko. He is visibly displeased by the news. Later on, after Tatsumaki unearths the Monster Association Headquarters, Metal Bat and his sister are seen watching news coverage of the event. Metal Bat discreetly throws his bag, containing his clothes and bat, out of the hospital window. A worried Zenko then asks him if the heroes will win and he reassures her saying that "Heroes never lose". He then gets out of bed, telling his sister that he is going to the bathroom, when in actuality he is going outside to retrieve the bag, change clothes and mobilize to combat the current threat in Z-City with the other heroes.

Psychic Sisters Arc
Metal Bat briefly appears to defeat a Dragon-level threat. He is angry because he is missing his cat giving birth. He plans to take his frustrations out on the monster but said monster is destroyed by Tatsumaki and Saitama during their fight and attempts to calm himself down afterward.

After this, Metal Bat decides to quit the Hero Association for unknown reasons and joins the Neo Heroes. When he visits the Neo Heroes' headquarters, he comes across Child Emperor and Superalloy Darkshine, who have also joined the Neo Heroes.