Not exactly, I recently read a Chinese translation of this doujin a while ago and the two on the cover are actually high school students named Re-chan and Koizumi Yukari respectively and that they're from a cosplay club.
Plot Synopsis It's a really dark story.It's an era where Renko and Merry (the real ones) are known as urban legends and Re and Koizumi found their clothes/documents in an abandoned school. So as a cosplay club with only the two of them as members, they cosplay as Renko and Merry and quote their lines from the music CDs despite none of them actually having any powers. It's later revealed that Koizumi started this thing as a form of escapism of sorts. Koizumi is a victim of child abuse and cosplays as Merry and seeks to make dreams a reality.Koizumi also does this to hide bruises. Re is really only in it for the ride and throughout the story progressively gets more annoyed at Koizumi referring to themselves as Merry and Renko. One day Koizumi's bruises become extremely prominent and misses school. At night in their secret hideout, Re tells Koizumi to give up this whole charade and Koizumi snaps and refuses to call either of them by their real names and still refers to themselves as the "Sealing Club" and "Merry and Renko". The next day Re decides that the clothes are part of the problem Koizumi's refusing to accept reality and cuts them off, tearing apart the "Boundary fabric" (previously they've been using this term to describe cosplaying as a means of escapism). However, in a twist, cutting off the dress reveals an unharmed and bruiseless Koizumi, who refers to herself as "Merry" and calls Re "Renko". Re is naturally shocked at this and wonders who this person is. "Merry" then drags Re to initiate the Sealing Club activity, leading her to an overhead bridge. "Merry" hangs over the rail, inviting Re to fall onto the oncoming traffic below. In tears, Re tries to prevent her from committing suicide and desperately tells "Merry" to call her by her real name instead of "Renko" while admitting her love for her. "Merry" responds with "Renko, who is Yukari?" and falls onto the oncoming traffic.The very next day, the news announce the discovery of a female corpse on the street as well as the disappearance of Koizumi Yukari. Re goes to her hideout only for the manga to reveal Koizumi, very much alive.In a surprising plot twist, it's revealed that Koizumi is actually a boy (the manga hides this in previous pages by not showing Koizumi's lower body when he's in his school uniform and every other time he's cosplaying as Merry). In the end, Koizumi decides to give up the charade and decides to report his child abuse to the police. Having accidentally summoned the actual Maribel Hearn, Koizumi then proceeds to destroy the clothes/documents relating to the Sealing Club, as his goals of realizing the urban legend of Renko and Merry have succeeded.