Endeavor's Trainees vs. Beros & Sidero

Endeavor's Trainees vs. Beros and Sidero is the battle between Endeavor's trainees Deku, Bakugo and Shoto, against Humarise agents Beros and Sidero.

Prologue
After Deku and Rody manage to escape with the briefcase, Humarise uses their contacts to have them declared criminals by the Otheon authorities. Endeavor demands the police commissioner to show him the evidence of such accusations, but since he is secretly a follower of Humarise, the commissioner refuses to collaborate. Meanwhile, Shoto is informed by Clair Voyance that the car that crashed near where Deku was chasing Rody was attacked by a Quirk, and that the driver, Alan Kay, was a member of Humarise. Furthermore, she also informs him that in an alley near the accident, they have found the briefcase with the stolen jewelry.

Shoto then receives a coded message from Deku informing him that he is heading towards Klayd. Shoto more or less deduces what is happening and recruits Katsuki to go to the border. During the trip the two recap the whole situation, coming to the conclusion that during the chase, Rody and Deku mistakenly took a briefcase related to Humarise, thinking it was the one with the jewels, and that the reason why the police persecute them is because several of its members are allied with the criminal organization.

Meanwhile, after several days of traveling, Deku and Rody manage to reach the border between the two countries in a canyon, but seeing that it is guarded by a large police force, they decide to cross the border through the mountainous area. While discussing about the best way to do it, they are spotted by a Humarise helicopter that flies over the area, which is carrying Beros and Sidero.

Battle
Beros starts shooting arrows at them from the helicopter, but Deku is able to quickly evade the projectiles, despite his injuries and having to carry Rody. Seeing his partner's frustration, Sidero suggests Beros to uses his Iron Balls instead. Accepting his suggestion, Beros uses her Longbow Quirk to fire the metallic spheres at Deku and Rody. The projectiles increase in mass and size considerably before impact, causing great destruction to the canyon walls, which is witnessed by people on the border.

Although the shots fail to hit Deku, they do manage to make him lose his balance and fall. Acting swiftly, Deku manages to use Blackwhip to latch onto the tail of the helicopter, attacking it with a Delaware Smash Air Force, causing the pilot to lose control of the rotorcraft. The recoil of the attack causes Deku and Rody to fall roughly to the ground, although fortunately they only get bruises. Rody realizes that he has dropped the briefcase, and when he goes to retrieve it, he is nearly crushed by some Iron Balls. The shock wave causes both him and the briefcase to almost fall off the cliff, holding on to the edge with one hand while holding the case with the other.

Sidero jumps out of the helicopter and lands right in front of Rody, ready to kill him with another one of his giant metal spheres. Despite the dire situation, Rody throws the briefcase at Deku, but Beros shoots several arrows at the young hero to prevent him for helping. Sidero is about to crush Rody just as he begins to fall off the cliff.

Fortunately, Shoto and Bakugo were at the border when the battle began, and seeing its destruction, they rushed to help. Shoto uses his Quirk to generate a large wave of ice that not only captures Sidero but also saves Rody's life. From the helicopter, Beros begins attacking Shoto with her arrows, but is interrupted when Bakugo appears and fires AP Shot: Auto-Cannon at her, damaging the chopper.

On the ground, the trapped Sidero is willing to surrender to Shoto in exchange for telling him everything he knows about Humarise and the briefcase, but Beros shoots several explosive arrows at him to punish him for his betrayal. After this, she continues facing Bakugo, who chases the helicopter through the air using his Explosions to propel himself and move through the air. Thanks to the great skill and control he has over his Quirk, Bakugo manages to dodge and destroy all the arrows she fires at him, until her quiver is empty.

Bakugo reaches the helicopter and orders her to surrender, since she is out of arrows plus the chopper is out of control due to the damage received during the battle. Finding herself cornered, Beros picks death over being captured and interrogated by the heroes. She proclaims her allegiance to the cause of Humarise and jumps out of the helicopter into the chasm, right before it crashes.

Deku, Bakugo, and Shoto are shocked by her apparent suicide.

Aftermath
Once the battle is over, Izuku meets with Shoto, Katsuki, and Rody, and catch up on the situation. Izuku realizes that the battle caused a secret compartment in Alan's briefcase to open. After getting far enough away from the battlefield, they find the compartment concealed a small puzzle-box.

The three students try to solve it without success, until Rody remembers that it is exactly like one his father had given him years ago, and manages to solve the puzzle and open the box, uncovering inside a strange device and a microSD. The four decide to cross the border to Klayd and investigate the information it contains.

Meanwhile, Flect Turn is informed of his followers' failure to retrieve the briefcase, but decides not to make a big deal out of it, considering it too late for the heroes to stop his plans, beginning the operation to save humanity.