Sousuke Mihara and the Paranormal Investigation Club finally meets the girl who inspired the story of the "Bare Legs in the Twilight", and in an unexpected surprise, also finds the elusive "Interdimensional 13 Steps" where she is found.
Sousuke finds himself awestruck in front of the mysterious girl behind the "Bare Legs in the Twilight". Then, with all of his courage mustered inside him, he asks the girl if she could go out with him. Of course, the girl was shocked by Sousuke's statement, and she almost fell the windowsill she was sitting on. Fortunately, Sousuke was able to hold on to her.
And there, he discovers that he can touch the "ghost" that he has thought about for a long time.
Teiichi, Yuuko and Kirie soon discuss their discovery at the Paranormal Investigation Club headquarters. Kirie is clearly disappointed that there are no ghosts involved in the case, and it is clear that she did not approve the upperclassman's actions. While Teiichi worries about Kirie's disrespect to an upperclassman, he continues with the report on what happened.
It turns out that the girl behind the "Bare Legs in the Twilight" is a third-year student named Minato Okiura, and she was quite surprised that someone else manages to find her "secret place". After Teiichi is introduced by Sousuke to Minato, the third-year middle school girl soon reveals that she belongs to the school's Art Club and she has been trying to draw the school.
Soon, Teiichi becomes curious towards a flight of stairs located inside the room, and before he could investigate further, Minato gives out a warning: that the stairs are the "Interdimensional 13 Steps".
Nonetheless, Teiichi proceeds on with Yuuko behind him.
Thirteen grueling steps after, there is a door at the end of the way, and when Teiichi opens it, he is shocked to discover that a three-storey fall awaits him in the end.
It turns out that the mystery is actually metaphorical, but in spite of stumbling upon a dead end, Teiichi still thinks that Yuuko is supposed to be linked to the flight of stairs they discovered. Kirie still has doubts, however. Soon, one last question remains: "How did Minato discover the hidden room?" Minato tells them that it was by accident, when she found an elderly woman in front of "The Jail". After following the elderly woman, Minato lost her at the end of the hallway on the third floor, and after investigating, she discovers the hidden room; in the end, she was unable to see the woman, and she concluded that it might be the ghost of the Interdimensional 13 Steps.
The story appears to alarm Kirie, but she and Teiichi was surprised when Yuuko tells them that the "Interdimensional 13 Steps" does not belong to the Seven Mysteries. After that, she takes Teiichi with him and leaves the clubroom.
Kirie is left troubled by their discovery of an elderly woman in the school's premises, and she decides to visit "The Jail" herself.
Meanwhile, Yuuko appears to be in high spirits, playing with Teiichi although they came up empty with the Interdimensional 13 Steps case. Soon, Yuuko tells Teiichi that she appreciates it if things do not change, but Teiichi tells her that he will continue investigating all seven mysteries... even with Yuuko's ominous warning that doing so will be his death.
Inside "The Jail", Kirie stands in front of the Interdimensional 13 Steps and trudges it nervously. As Teiichi discovered earlier, there is a door leading to a dead end. But when Kirie goes and looks around where the staircase ends, she finds a secret door that exposes another flight of stairs. Convinced that this is the real Interdimensional 13 Steps, she heads on.
A bright light welcomes her, and it is truly another world at the end of the mysterious staircase.
As the final school bell tolls, a figure emerges from behind Kirie, and to her surprise, it is none other than her grandmother.
Before Kirie could ask about Yuuko, she is told to go home. It turns out that her grandmother knows of her involvement in investigating Yuuko, and points out that there is nothing that can turn back what happened to Yuuko. She then requests Kirie to keep herself away from being involved with Yuuko.
The sad expression on her grandmother's face made Kirie uneasy through her way out of school, and as she ponders on her next step, she thinks of Yuuko... and her grandmother's sadness every time she talks about Yuuko.
By order of appearance
- Minato Okiura
- Kirie's grandmother
- Paranormal Investigation Club Headquarters, Old School Building
- Hidden Room, "The Jail"
- This chapter's cover shows Yuuko ascending a version of the Penrose stairs, an impossible object which involves a staircase that goes on an endless loop.
- Yuuko plays with the words "stairs" and "ghost story", which are both kaidan in Japanese.
- Did Minato accept Sousuke's proposal to go out with him?
- What is the real connection between Yuuko and Kirie's grandmother aside from being sisters?
- "PLEASE GO OUT WITH ME!!" — Sousuke's proposal to Minato upon their first encounter
- "Ah. You should be careful of those stairs. Because those are the Interdimensional 13 Steps." — Minato's warning to Teiichi regarding the flight of stairs inside the room
- "It'd be nice if things were like this forever. Nothing has to change. I'm sure that we're happiest with the way things are now..." — Yuuko's wishful remark to Teiichi on the current state of things
- "...Teiichi-kun, does that mean you would die for me?" — Yuuko's ominous question to Teiichi
- "...I don't know why [you are investigating about Yuuko], but... how she lived or how she died... knowing that won't change the fact that she's dead." — A stern remark pointing to Kirie's involvement in investigating on Yuuko's death from her grandmother