The first chapter of Toaru Nichijou no Index-san was released on September 12, 2013 in Monthly Shōnen Gangan.
Alone in Touma's apartment, Index is happily helping herself to a pudding. She then notices something written on the side - 'Do Not Eat'.
Index thinks to herself about how Touma is always going off and leaving her alone. Annoyed, Index decides to make him pay when he gets back. At that moment, Touma returns and Index greets him with a smile.
As Index welcomes Touma back, she notices he's hurt. Touma says its just a scratch but reveals something which concerns Index even more - he wasn't able to get any ingredients for dinner.
After biting Touma, Index complains that he's changed, saying that he used to prepare delicious food when they met. She tells him to remember the time when they met, to which Touma asks why she's talking like they are a couple. Index then assumes the position she was in on the railings when they met, saying that he shouldn't forget the original intent.
In response to Index's complaints of hunger, Touma decides to go to the convenience store. Index asks if she can come along but Touma says he's going alone, to her disappointment. Index says that if she goes they won't forget anything because of her perfect memory.
At the store, Index can't decide between omusoba and omuyashi. Touma picks the omuyashi and says he'll share the omusoba with her. Index then asks if he'll forgive her if she eats it all.
Index brings Touma some yakisoba, the same food from when they first met. Thinking that it wasn't quite the same as the one back then, Index steps on it to make it so, to Touma's dismay.
As they head home, Touma thinks about his ever-decreasing funds and wonders if Index is actually a goddess of poverty. He then touches her forehead with his right hand to check, but as expected nothing happens.
Imagine Breaker (イマジンブレイカー Imajin Bureikā?): With Index full and content, Touma remembers the pudding he had left in the fridge and looks for it. Index chooses this moment to confess to eating it, saying that Touma thought he'd put the pudding in the fridge but she'd dispelled that thought with her spoon, to his annoyance.