Kuroko and Uiharu spots a car thief and rushes in to apprehend him, ignoring Uiharu’s warning that he might have accomplices. Kuroko gets knocks back by a second guy who also attacks Uiharu with a taser while escaping. Uiharu becomes unhappy with Kuroko for her recklessness, and matters get serious when she realises that Kuroko has forgotten about a promise they made before. Back in the dorm, Kuroko is visibly bothered by the falling out with Uiharu, which annoys Misaka. Kuroko then relates the story of how she ended up as partners to Uiharu initially.
As a junior in Judgment, Kuroko was paired with Konori and restricted to mostly menial work, which made her slightly unhappy. They had a chance encounter with Uiharu in a post office, which also happened to be the target of robbery. Instead of waiting for backup, Kuroko rushed in to take down the robber, only to realise that he had an accomplice who had taken Uiharu as a hostage. Trying to attack the robber, Kuroko overlooked the fact that he might have offensive abilities and Konori got injuring shielding Kuroko from an explosion. Aware that it was her recklessness that led to this situation, Kuroko was determined to save Uiharu by teleporting her outside, even if she got beaten up badly in the process. Impressed by her ability, the robber invites Kuroko to join him, but Kuroko sticks by her ideals. Just as the robber uses his final attack on Kuroko, a mysterious railgun attack was fired from outside, saving Kuroko and giving her the opportunity to apprehend the robber. At the end of the day, Uiharu and Kuroko swore to stay true to their ideals and to work hard towards becoming full-fledged members of Judgment.
Finally remembering the promise, Kuroko is too embarrassed to face Uiharu, but urged on by Misaka, she teleports away to join Uiharu in apprehending the car theives after the latter has located their hideout location.