From Baka-Tsuki:

The young girl appeared at the end of summer.

We had been very close childhood friends, regardless of time. However, as we became high school students, the close distance we once had when we were play pals were gradually increased, setting us apart. Yet, in a bid to grant the wish of “Menma”, the young girl who was the only one unchanged, the six of them gathered once again. This is the novel written by the screenwriter, Mari OkadaFuji, of the anime aired on Fuji TV NOITAMINA. We had been very close childhood friends, regardless of time. We formed the ‘Super Peace Busters’ and had always played with each other. However, when we had become high school students, we were poles apart. Jintan became a shut-in. Anaru endeavoured to meet the expectations of her female friends. Yukiatsu and Tsuruko entered an elite high school. Poppo gave up studying and travelled around the world. Finally, the only one unchanged, a girl called Menma, suddenly appeared in front of Jintan, hoping he can help her to grant her wish. With this turning point she induced, the six of them gathered once again