This is a story that may or may not have happened. Hypothesis drift in space-time. Abstract theories wander the dimensions. But stories... they travel from heart to heart. "Barriers, huh?" The girl pondered. Ever since a certain historic event occurred in the past, it is now typical for humankind to perceive things in terms of barriers. This is both a new and an old way of seeing the world. People sometimes say things like "a barrier has been found" or "a barrier is forming." But to be precise, it should be said that the perception has changed (the facts remain the same). ...This is what Renko Usami was pondering.

Renko Usami is a member of the occult circle known as the Secret Sealing Club. She goes by the name Renko. It's amazing to think that she has the ability of a built-in atomic clock (on JST) and GPS in her eyes. But it's also quite creepy! (M.H.) Maribel Hearn is a member of the occult circle known as the Secret Sealing Club. She goes by the name Merry. It's amazing to think that she can see all sorts of phenomena that take place inside barriers. But it's also quite creepy! (R.U.)

Renko Usami is a genius. She and the people around her might not even be fully aware of this, but she's probably the most intelligent person of her generation (a simple comparison would be difficult, but Planck is also one of the most intelligent people humankind has ever seen). However, nowhere is it said that a genius has to be good. Nor can one say that the goodness in a genius exists because they are a genius. The child prodigy in her that can be compared to a lion or a dragon, is just the tip of the iceberg. Most of her potential is currently in the midst of a deep slumber. But none of that matters. Such things don't make a difference to Renko Usami. She only relies on the vigor and spirit of her youth. She does not falter in the face of danger, nor does she pay heed to criticism. Renko Usami is not afraid of stupidity. This is unmistakably the only choice a clever girl like her could make.

Kekkai, the Japanese term for barrier, is an archaic word that is defined as a concept of demarcation with influences of classical religion. It usually refers to something that is defined as a spatial "boundary." Since it is something that clearly differentiates between the inside and the outside, it is a concept that defines a "line" between the two. People generally stopped believing in the existence of barriers in their classical religious sense. ...But that has changed now. As the fundamental principles of super-unified physics were announced, people started accepting them as truth. At the same time, people with the ability to perceive barriers began appearing all over the world. It became clear that a large percentage of people possessed some sort of ability. It was also found that there are plenty of barriers around the world, and holes may open in them that can cause peculiar phenomena. Various phenomena of unknown cause and principle (including psychic phenomena and paranormal phenomena) are not unscientific. They are super-unified physics phenomena that have been overlooked because people could not perceive barriers.

Merry finally managed to turn the tombstone around 60 degrees while giving side glances to Renko, who was carelessly stargazing as though she had all the time in the world. Merry was doing something quite daring. But adding one more crime to the list after pulling out inscription plaques wouldn't make much of a difference anyway. And Renko would be held responsible for half of it. "But, Renko... I don't really think it's right to label a strange phenomenon that occurs on the other side of a barrier as a super-unified physics phenomenon. By the way, come help me." "Why do you think that?" "Come here and help me first." Strange phenomena occurring on the other side of a barrier might include super-unified physics phenomena. But that doesn't mean they are limited to them. They also have things that are unknown to super-unified physics. "2:30 sharp!" "Come help!" "Merry, look!" A panorama of cherry blossoms spread out across the autumn night. They were clearly seeing another world. What do you think, Renko? Does this also fall under super-unified physics? "―How beautiful."