Promise to Sing (歌う約束 Utau Yakusoku?) is the seventh chapter of the Toaru Majutsu no Index: Miracle of Endymion manga, released on August 12, 2013 in Monthly Shōnen Gangan.


As Ladylee's ritual begin at the same time as Arisa's concert, Index and Touma approach the Endymion using the Ballistic Slider. Index is amazed by the large spell she is witnessing, to which Touma asks if they are still able to save Index, to which she says they still can. Just then, the Endymion's anti-debris missiles activate, but they are however informed by Motoharu not to worry about it as Kanzaki Kaori is on board. There, she easily destroys the missiles and falls down back to the earth, counting on Touma to finish the rest.

As Arisa continues her concert, Shutaura arrives via the high-speed elevator of the Endymion and makes haste. Below, the Aiho and Anti-Skill are having trouble with the large mobile weapon and is unable to go through the bridge, that is until an irritated Mikoto arrives with Kuroko and destroys the mobile weapon with her Railgun attack. She asks Kuroko to defend the bridge, though Kuroko is hesitant, Mikoto insists and goes on her way into the space elevator. Also, Stiyl and the witches as well are doing their part, but they are not unnoticed.

Ladylee notes the ruckus the people below are making though is convinced that her plan will come to fruition. She is however interrupted by the arrival of Shutaura. Ladylee's mockings of her has no effect as Shutaura shoots at her over and over again until she is forced to change magazines. Still, Ladylee survives, and recalls of the time before she was immortal, in a long forgotten count of years, she accepts ambrosia from a wounded Crusader. Coming to, Ladylee says that she has lived long enough and activates the spell of the Endymion. Shutaura tries to stop her but is interrupted by the male of Automaton. Finding herself in combat, Shutaura uses her Earth Palette on the Automaton. However, the explosion is so great that it opens up a hole in the Endymion. Ladylee and her Automaton is flung into the vacuum of space while Shutaura is forced to use her cables in order to not get dragged away.

Not only does Touma and Index feel the stress of the explosion but Endymion as well. And Kazari notes, much to everyone's horror, that the space elevator will collapse to the Earth. Back with Arisa, she awakens to her concert hall falling apart and her audience falling into despair. As the crowd panics Arisa does the only thing she knows she can do: sing. Her song soothes the hearts of the crowd and finally the staff is able to start evacuating them peacefully. Meanwhile, Ladylee, surviving the vacuum of space, crawls into the core room, the center of her spell, and activates the next phase of her plan. still determined to die and take everyone with her no matter what.

Touma has a call from Motoharu detailing that the Endymion is about to collapse and that there is no way to prevent it. However, their conversation is cut short afterward. In an impasse, Touma tells Index that they should split up, with him going to Arisa and her going to stop the spell. Index tells Touma that they must absolutely save Arisa as they still have to sing the new song Arisa wrote, to which Touma assures her. Thus, the two split up, determined to save their friend.

Adapted FromEdit

Major eventsEdit

  • Arisa begins her performance in Endymion but is interrupted by it breaking apart.
  • Touma and Index arrive at Endymion to stop Ladylee.
  • Shoutaura arrives at Endymion to stop Ladylee.
  • Mikoto, Kuroko, Kazari, and Ruiko arrive to assist Anti-Skill. Stiyl and his three witches arrive below Endymion.


New CharactersEdit

No new characters were introduced this chapter.


New AbilitiesEdit

  • Unnamed ritual with the Endymion and Meigo Arisa's powers - Ladylee Tangleroad and Meigo Arisa


New LocationsEdit

No new locations were introduced during this chapter.



  • Index references the song Arisa begins writing back in Chapter 3.

Cultural ReferencesEdit

  • Ladylee references Ariadne as the ritual on the Endymion continues.
  • Index references Goetia when talking about Ladylee's large magic circle.
  • The Crusades is shown, as well as ambrosia.

Unanswered QuestionsEdit

  • How did Kanzaki survive the vacuum of space? And where did she go to after destroying the missiles?


  • Motoharu: "Nee-chin! It's your time to shine!"―said to Kanzaki as she exits the Ballistic Slider.
  • Kanzaki: "The rest is up to you... Kamijou Touma..."―said to Touma as she falls back to Earth.
  • Arisa: "Yes... That's right... This is why I exist... to sing..."
  • Ladylee: "Well... I guess I've lived for at least a millennium now. My experiment on the Orion failed... But I attained an unexpected by-product. It is Arisa... And it's through her power over miracles... that I can finally die...! Come now, let us all die together!! This star, and everything else... I'll make you all accompany me!!"―said to Shutaura as she activates her spell on the Endymion.
  • Index: "Hey, Touma. We absolutely have to save Arisa. We promised! We're going to sing her new song together!"―said to Touma before splitting up in the Endymion.
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