This article describes the story of Evanescent Existence in detail.
One day, several humans from the Outside World are spirited away to a strange land called Mugenri. Although nobody knows where they are, they all want to get out. One of these humans is an inventor named Tsubakura Enraku. Their best friend, Yabusame Houlen wasn't spirited away like the others, but has the power to cross over dimensions. Now, Yabusame has to cross this strange land in order to find their friend.
Yabusame gets lost in Mugenri. As they decide to reach the "goal" in order to get out, on their way, they meet some of their friends (Kurohebi and Aoji Shitodo) which they battle, and beat in the end. They then find Tsubakura, who is acting strange. After defeating Hooaka Shitodo and Kuroji Shitodo, Yabusame finds a "black sun with a torii floating in it. It's there where the most annoying of annoying people they know is found. It's there where they're encountered by Clause, who believes that getting out first by going through the "Black Star" gives power. They fight and Yabusame is victorious.
Tsubakura's scenario is chronologically before Yabusame's. They encounter the same people as Yabusame, where everyone notices that they are not acting like usual.
After the events of Brilliant Pagoda or Haze Castle, Suzumi, specifically Cine Hamal, uses their powers to visit past memories through reading a book containing someone else's memories to collect information on the events that happened in this game, i.e. Yabusame and Tsubakura's scenarios. Cine Hamal also has the personal goal of finding Tsubakura Enraku, presumably for the "joy" of torturing them, although this never comes to pass.
In Yabusame's bad ending, they wake up in their home at the Outside World and decides to try again and save Tsubakura.
In Tsubakura's bad ending, it's shown that somebody has been impersonating Tsubakura all along, and after being defeated by Clause, they regain their real appearance. Realizing that they have been overestimating their opponents, the person disguises themself as Tsubakura again.
In Suzumi's bad ending, they suddenly jolted awake in their house with Arde asking Cine Hamal why they were done so quickly. Cine Hamal reveals that they left halfway through and Arde tells them to go back again, Suzumi activates their power and loses consciousness once again.
In Yabusame's good ending, they don't know what to do and heads for the mysterious sun because they can't think of any better solution.
In Tsubakura's good ending, it's shown that they are actually a priest named Tsurubami Senri who was disguised as Tsubakura. Because they didn't know of their personality towards others, everyone suspected it. Without their disguise, Tsurubami decides to wait for the others so they could reach the "goal".
In Suzumi's good ending, Clause accuses them of not being the real Suzumi, which was false. Suzumi (Cine Hamal) stares at the Mugenri Barrier and ponders about the conditions needed to go through it, before deciding that they couldn't be bothered and that stuff like this is best left to Arde. Suzumi, hoping to encounter Tsubakura within, enters the black sun.
Yabusame and the real Tsubakura cross into the "goal", which is the Shrine Road, where Tsurubami is waiting for them.
In Tsubakura's scenario, it's revealed that they crossed the airspaces with ease, since Yabusame and Tsurubami defeated everyone. After defeating a stronger Clause, Tsubakura reaches the Senri Shrine, where they meet Tsurubami, who reveals that they had caused this all because they wanted a new protector for Mugenri, but not before testing Tsubakura's powers first. After Tsurubami is defeated, they see that Yabusame is coming into their direction and Tsubakura asks the priest to give them a hard fight.
In Yabusame's scenario, after defeating Clause, they reach the Senri Shrine, where they encounter Tsurubami Senri. Because of their similar appearances, Yabusame mistakes them at first. After introducing themself, Tsurubami has a fight with Yabusame to test their power. After a long and difficult battle, Tsurubami is defeated and proclaims both Tsubakura and Yabusame as the new protectors of Mugenri, they want to tell this to Tsubakura but the young scientist was already gone, but not before leaving Yabusame a mocking note.
In Suzumi's scenario, after defeating Clause, they reach the Senri Shrine, where they encounter Tsurubami Senri. They question each other about their actions and motives, with neither giving an answer. Suzumi hoped to use Mugenri's spell card rules to force Tsurubami to speak, but since they were technically outside of Mugenri, the plan backfired. They thought about killing Tsurubami, but was reminded by them that they are too weak to be able to do so. Although frustrated, Suzumi let Tsurubami escape.