Tank Topper Army

Tank Topper Army (タンクトッパー軍団, Tankutoppā-gundan) is an organization comprised of Tanktoppers, under the leadership of Tanktop Master. After the incident with the Monster Association, many of its members quit along with Tanktop Vegetarian.

Appearance
The most distinguish feature of the Tank Topper Army is that every member wears a tanktop, with some having different markings and prints, while other wear it plainly.

Rumored Monster Arc
Tanktop Tiger was asked by a civilian about a suspicious person, the person being Saitama. Tanktop Tiger immediately yells out his names introducing himself to Saitama and disregard him of being a new hero. Tanktop Tiger taunts Saitama to look better, but was cut off by Speed-o'-Sound Sonic, who threw exploding shurikens at him, leaving him unconscious.

Giant Meteor Arc
After the meteor was destroyed by Saitama and heavily damaging Z-City in the process, Tanktop Tiger confronts Saitama with his older brother Tanktop Black Hole. The pair accuse Saitama for taking credit of S-Class heroes to jump ranks. Tanktop Black Hole uses his loud voice to gather a mob around them, chanting for Saitama to quit being a hero. As the mob is chanting against Saitama, Tanktop Black Hole deceives the civilians into thinking Saitama tries to attack them. The brother try to challenge Saitama to "protect" the civilians as part of a publicity stunt, but were easily defeated with Tanktop Black Hole apoligizing profusly.

Alien Conquerors Arc
Tanktop Master attends the S-Class hero meeting, there he recognizes Saitama's name, but is unable to recall where he had heard it. During Dark Matter Thieves invasion on A-City, Tanktop Master attempted to assists Tatsumaki, but failed after realizing he was no match for her psychic powers.

The Hero Hunt Arc
Tanktop Vegetarian happened to encounter Garou, who began his hero hunt and was easily defeated by him. After being released from the hospital, Tanktop Vegeterian, alongside the entire Tank Topper Army, track down Garou who was about to fight Mumen Rider, but was struck immediately. As Garou declared to kill every member, Tanktop Master punched him and used Tanktop Tackle, but to his surprise Garou was able to stand. Tanktop Master and Garou fight briefly, with Tanktop Master having the upper hand. As he was about to finish the fight, Mumen Rider steps in, stopping the fight, believing Garou had already taken enough beating, to which he agrees. However Garou chose not to stop and used Water Stream Rock Smashing Fist and easily defeated all the members, Mumen Rider and Charanko.

Monster Raid Arc
Monsters attack the hospital Tanktop Master and Mumen Rider are staying at.

Big Construction
The tanktoppers are seen training after the battle with the dark matter thieves, when a mysterious vehicle appears outside the hero association hq and the tanktoppers are asked to defeat it. The giant vehicle launches several drones and only Tanktop Master is able to defeat one. It is later revealed that the vehicle and drones belong to Metal Knight who later cleans up the city in a week.

Trivia
A running gag for the Tank Top Army is that they are always beaten or humiliated.
 * Tank Top Tiger gets hit by Sonic's Exploding Shuriken.
 * Tank Top Tiger gets punched by Saitama during the Meteor Arc and Tank Top Black Hole has his hand crushed by Saitama begging for mercy.
 * Tank Top Master felt weak when Tatsumaki was able to pick up thousands of rubble pieces right after Tank Top Master threw one himself. He felt the same way again after Metal Knight came back to rebuild A-City.
 * Tank Top Vegetarian got pummeled by Garou, and then punched in the face again by Garou.
 * Finally, TankTop Master was defeated and hurt pretty bad after Garou started using his Water Streaming Rock Smashing Fist.
 * Then Garou used Water Streaming Rock Smashing Fist to beat up the remaining members of the Tank Top Army.
 * Despite being beaten up and humiliated they're still one of the strongest factions of the Hero Association.