Heartwarming / A Certain Scientific Railgun

• Episode 10: When Uiharu gives Saten a speech amounting to a combination of You Are Not Alone and You Are Better Than You Think You Are after Saten admits that she's used Level Upper because "Level 0 's are defective", moments before she falls into a coma.
  Uiharu: I'll wake you up, Saten-san!
  • There's also Misaka telling a physically worn down Kuroko that as her junior she can rely on her Onee-sama.
• Surprisingly enough, the beach/swimsuit episode had one near the end, Mikoto doesn't seem to enjoy herself very often due to being "embarrassed" of her "childish" tastes, When near the end she was having fun prancing in her frilly swimsuit it was kinda cute, almost made up for the squick the rest of the episode had. (Keyword being ALMOST)
  • Uiharu being the only one to find Mitsuko's pet python Ekaterina-chan cute and petting her at the end of the episode.
• "Erii, thank you for hearing my voice."
• The end of episode 24, where Kiyama's students requisition a blimp to wish her happy birthday.
  "We love you, Kiyama-sensei!! Get Well Soon!!
• So many scenes involving Kiyama and her students counts as this.
• Also in the manga, we get to see the Sisters arc from Mikoto's view. At the bridge scene, she's just realized none of what she's done has even slowed down the project at all, and has managed to convince herself that letting herself get killed is the only choice she has left. After all, its the real world, and there aren't heroes around to just fix everybody's problems. Then Touma walks up.
  Mikoto: [thinking] I know how this looks. He must think I'm involved in the experiments. He must think I'm a monster.
  Mikoto: [out loud] I guess you found out, huh? You here to yell at me, call me a monster for letting these experiments continue?
  Touma: Isn't it obvious? I came here because I was worried about you.
  • Keep in mind that that Touma had recently lost his memories and has no idea who Mikoto is and what is their relationship. Despite this, he immediately sees her as his friend and vows to help her carry the burden of saving her clones.
• Mikoto telling Accelerator that she's not working to stop the experiment out of jealousy, envy, vanity, or a desire for power; it's just that the clones are her sisters, and it's her job to protect them. The stunned look on 10032's face says it all.
• Misaka 10032 explaining to some kids that Mikoto is the elder of the pair.
  10032: While it is true that she has a childish taste that isn't suitable for her age and she's crude, short-tempered, quick to pick fights, and on top of that, is someone who can't admit she likes what she likes, she's a troublesome big sister who would throw away her life for Misaka.
• Touma calls Mikoto by her name for the first time.
• A comment from Mitsuko finally convinces Mikoto to involve her friends in her adventures. She tells them about the Dark Side of Academy City... and they agree to join her without hesitation.
  • They don't even let her finish warning them about how dangerous it is before they start talking strategy, completely ignoring her warnings.
• Episode 24 of Season 2. MISAKA 19090 explains to Shinobu why they're helping out:

  "Those girls are using the same base program as us. In that regard, they're our little sisters. Do older sisters need a reason to help their little sisters?"

  • Also, 19090 (and by extension, all of the MISAKA network) to Shinobu: "Thank you for giving me a heart." Which shows that Shinobu's plan to give them free will did work, just not to the extent she'd hoped for.
• Railgun T, Episode 3: During Daihaseisai, MISAKA 10032 was mistaken by Mikoto's schoolmates and replaced her for an event. Even though she fails, Mikoto is not angry at her clone and simply asks her whether is she enjoying the festival or not.
• Railgun T, Episode 9: Saten's first meeting with Touma. The latter is a participant in the Borrowed Item Race and much to his misfortune, the item he required is a good luck charm. Being in a city of science, such an item is nearly impossible to find and by coincidence, Saten has one. Though hesitant to lend an important item to a stranger, Saten eventually relents after seeing his perseverance and remembering that he will still earn some points even if he is in last place. In turn, Touma is grateful to Saten for helping him and is careful not to touch the charm with his right hand, not wanting to negate any of its properties. It is this coincidental meeting that eventually leads Touma to get involved with Gensei's plan for Misaka. Without knowing it, Saten sows the seeds for Gensei's defeat (even when he has thought of Touma's involvement) and saves the city.
• Railgun T, Episode 10: The time Misaki and Dolly play together until the latter's death.
• Railgun T, Episode 11: Misaki realizes she needs backup, but can't use Anti-Skill, since they'll be slaughtered. She's about ready to give up on getting any help... and then she spots Touma. She smiles fondly before aiming her remote to contact him.
  Misaki: You really are a ridiculous knight... always appearing where you're needed.
• Railgun T, Episode 14: After Touma manages to end the Level 6 experiment on Mikoto, he gives her another You Are Not Alone speech to her in regards to the Darkside of Academy City and that she can always count on the people around her, himself included.
  • Also, Touma's dance with Mikoto during the bonfire ceremony, with Saten and Uiharu fully supporting them.
• Railgun T, Episode 15: Reunion of Mitori and Misaki with Dolly, whose memories are in her new body.
• Railgun T, Episode 25: Misaka presenting MISAKA 10032 to Kongou as her little sister, Mitori and Misaki taking Dolly to the aquarium and Doppelgänger telling Kuriba all the data and simulations she gathered to give her the chance to save her mother.
• Brief moment of Odd Friendship between Mikoto and Saiai in Dream Ranker arc, as they bonded over similar insecurity about their size (or lack thereof) and formed a temporary alliance to acquire a rare Indian Poker card named "Bust Upper" (which they failed to do). Heartwarming especially near the end of Chapter 79 of the manga, where Mikoto is telling Kuroko a long story about her experience with Saiai, someone she has just met, as if she's her friend (Mind you, Mikoto kept talking about Saiai until 3 o'clock in the morning!). This shows that if it wasn't for the harsh reality of Academy City's dark underbelly, Mikoto would've got one more friend that she can relate to.
• Railgun manga Chapter 97.5 shows Uiharu taking Saten to visit many urban legend spots in Academy City, because Saten looks depressed. Saten then tells Uiharu a story about how her new friend from Dark Side suddenly stops visiting her. Saten then pleadingly asks Uiharu to not suddenly disappear from her life. Uiharu, despite knowing the difficulty to keep a promise about uncertain future, still complies, which brings a heartwarming smile on Saten's face.