The Adult World is the second chapter of Hinamatsuri manga series.
While discussing how the two can live together, Nitta makes Hina promise not to use her powers and she agrees. The two visit Nitta's boss in the hospital, where he gives Nitta the task of finding a cheap way to clear land for development. Hina unexpectedly releases a blast of psychic energy and reveals that if she doesn't user her powers often enough, she loses control of them.
Seeing the explosion as an attack on their boss from a rival gang, Nitta's gang prepares for retaliation. Having captured the criminals, the gang's acting leader, Kiyoshi Baba, cannot discern who the culprit is. Nitta knows this is because none of them are responsible for the explosion and drives to the scene with Hina in tow. One of the captured men react to Hina's presence, as she had destroyed their base previously, and Baba assumes this is the man responsible for the attack.
Later, Hina uses her powers to perfectly clear a plot of land, much to Nitta's delight. He takes her out for her favorite dinner, salmon roe, and explains to Hina that, in the world of adults, people are rewarded when they do a good job. Hina thinks that this means that she's now a woman, which Nitta rebukes.