Unlike past installments of the series, Corpse Party -THE ANTHOLOGY- Sachiko no Ren'ai Yūgi ♥ Hysteric Birthday 2U only has one Extra chapter in it.
#EX; Those Were Our GravesEdit
The chapter begins with a scene in which Azusa Takai, Ran Kobayashi, Toshihisa Goto, and Kentaro Oshio perform the Holy Shroud's Promise ritual near a river, which if performed successfully, can make the performers become friends forever and washes away bad signs. Azusa and Ran will be transferring schools to St. Cruz Girls' High School in the city, leaving their hometown in the village.
The scene then cuts to when Ayumi Shinozaki and Yoshiki Kishinuma were still trapped in Heavenly Host Elementary School, separated from Satoshi Mochida and the others. Ayumi gets possessed yet again, which Yoshiki is shown to be tired of, however luckily for them Azusa arrives and exorcises the evil spirit that possessed Ayumi. Yoshiki mentions that they were sent to Heavenly Host Elementary School after performing the Sachiko Ever After charm, of which, Azusa commented that it's somewhat similar to a ritual from her hometown village.
Ayumi and Yoshiki then properly introduce themselves to Azusa. Azusa comments that Yoshiki must protect Ayumi and live up to his name (referring to "Kishi" in his name, which may mean "knight"). Yoshiki then clarifies that she is mistaken, and that "Kishi" in his name refers to "swamp" instead. Azusa chuckles and quickly learns that Yoshiki is head over heels with Ayumi, and how Ayumi is oblivious to his feelings and sets her eyes on Satoshi, and teases him.
The three people then exchange information of what they have gathered. Azusa takes out a notebook containing Ran’s student ID, and explains that she found it and is unsure whether she’s still alive. Ayumi takes the student ID and suddenly feels choked up and experiences a strange sensation. After she calms down, Ayumi explains that she can see Ran after touching Ran’s student ID. Hearing this, Azusa takes out her cross, which is glowing mysteriously. Azusa comments that Ayumi has a considerable amount of spiritual power. Azusa and Ayumi understand that what she experienced was psychometry, the ability to sense strong residual thoughts that had seeped into an object or the air. Yoshiki flips Ran’s notebook and is startled by numerous photos showing Azusa and Ran together. Azusa comments that Ran is her friend after a bit of pause. Ayumi offers Azusa to help search for Ran along with Yoshiki.
The three later investigate one of the classrooms after noticing a faint blue glow from its window. When they decide to examine the cleaning supplies closet, Ayumi feels a presence of a ghost inside and decides to get away from it. However, Azusa approaches the closet and finds Ryou Yoshizawa hiding in it. Ayumi warns Azusa and Yoshiki to get away from him and not look at him in the eye, but Azusa doesn't listen and comforts Ryou, who suddenly leaves.
They then examine a vase of a flower lying on top of the table. From it, Ayumi, Azusa, and Yoshiki are able to hear Kentaro's residual thought, which yells at Azusa that she's not a demon and that it's not strange for a man to like growing flowers. Azusa whispers Kentaro's name and shivers with a cold expression. When they all leave the classroom, Azusa notices a piece of cloth used to perform the Holy Shroud's Promise ritual further down the dark corridor. As she approaches the cloth, she almost falls down into a hole, but Yoshiki saves her. Azusa brings the cloth she has just retrieved to Ayumi, but Ayumi can't read the residual thoughts clearly.
Azusa then notices a figure down in the hallway, and produces a flashlight from her bag. They then encounter Ran, and Azusa rushes to her and hugs her, feeling relieved that she is safe. Azusa then notices that Ran's eyes are swollen from excessive crying, and when she turns her head, she sees Kentaro's corpse and screams. Ran explains that Kentaro's body was suddenly surrounded by black mist which entered his nose and mouth.
As they grieve for Kentaro's death, Azusa prays for Kentaro. Ran later gives Azusa Kentaro's cloth and says that he was sorry for not being able to keep his promise. Azusa disagrees and says that Kentaro is the most faithful person among them. It turns out that the piece of cloth that they have found earlier belonged to Toshihisa. Suddenly, the corridor becomes bright and the cloth Azusa holds is glowing. The cloth then projects an image on the wall, which shows a scene when Azusa, Ran, Toshihisa and Kentaro performed the charm. Azusa is surprised and seems uncomfortable with Ayumi and Yoshiki watching the scene.
On their way back home after they finish performing the charm, Azusa and the others hear the local farmers complaining that the water doesn't come out. Suspecting that the shrouds may have clogged up the irrigation pipe, they inspect the irrigation pipes and find the shrouds are stuck in the pipe. Kentaro suggests for everyone to apologize together, but Azusa, who was the one in charge of performing the charm, refuses and claims that the charm was a success and denies that they had messed up the charm. Azusa then runs away and Toshihisa follows after her after telling Kentaro to take care of Ran, who passed out.
Azusa blames herself and the charm, and that she is the one responsible for the death of Kentaro and them being trapped in Heavenly Host Elementary School. Azusa says that she received a call from her school about what happened and Kentaro was the one who apologized instead, claiming that the charm was his fault and the others were not involved. Since then, they were in awkward terms with each other until Azusa and Ran's school transfer. Yoshiki says it shouldn't be something for Azusa to be really upset about, and that Kentaro protected Azusa on his own will with no regret, and that he was happy for doing it, which reminded Azusa of Kentaro's death.
Yoshiki then notices someone coming towards their direction from the far corridor, who turns out to be a severely injured Toshihisa. Toshihisa then yells to Azusa to stay away from Ran. Azusa comes after Toshihisa to treat his wounds, but Ran held Azusa back and says that Toshihisa has been acting weird and is dangerous. Azusa is flustered as Toshihisa and Ran accuse each other. Both Yoshiki and Ayumi are confused as well, and when Ayumi questions Azusa about why they are fighting, Azusa snaps and yells at her.
Suddenly, the shining light on the wall brightens. Kentaro wakes up from his "death" and pleads to them to stop the fight. However, Kentaro's body is now floating in the air and the Holy Shroud's Evil Spirit takes control of Kentaro's body. The now possessed Kentaro laughs maniacally and claims that finally Kentaro's body has become its own. Azusa claims that he is no longer Kentaro. Possessed Kentaro attacks Toshihisa with black mist and manages to reflect Yoshiki's attack.
He reveals that Ran had pushed Toshihisa into a hole from behind out of jealousy because he was too close to her "Wife," and that she wants Azusa all for herself. Azusa is shocked to hear the truth when suddenly Toshihisa's cloth shines and projects the residual thought on the wall for everyone to see. Azusa shakes Ran, trying to deny the fact that what possessed Kentaro said was true, but Ran was unable to deny the claim. As everyone is in disbelief of what Ran has done, Kentaro laughs and reveals that Azusa is "the actress." The scene projected by Toshihisa's cloth then changes into a different one. In that scene, Azusa and Toshihisa are kissing, but then Azusa attempts to break up with him, saying that she just wants to be friends with everyone. But possessed Kentaro then reveals that Azusa confessed to Kentaro the next day, and was rejected. Azusa planned to restart everything at her new school alone. Hearing this, Ran then questions how she fits with Azusa's plan.
Azusa, who was shocked that all her plans were exposed, punched Ran in the face until her nose was bleeding. Azusa drew out a knife out of her cross and planned to kill Ran for being a nuisance. Ayumi attempted to stop her, but Azusa yelled at Ayumi to get away from her. Azusa claims that her being trapped along with the others in Heavenly Host Elementary School is not part of the "plan" and she yells to be sent back to the real world now. Ayumi asks what Azusa is talking about, but Azusa pushes her down until her head hits the floor and passes out. Azusa feels foolish for believing in evil spirits and she kicks Ran repeatedly. Yoshiki then uses possessed Kentaro's vulnerable moment to his advantage and stabs him with Azusa's dropped cross-knife. Yoshiki then yells at Azusa to exorcise the evil spirit.
With the friendship between Azusa and her friends broken and distrust for each other, everyone goes their separate ways. Azusa tries to advance with Yoshiki to get him on her side, which Yoshiki rejects strongly. Not giving up, Azusa tries to reason with Ayumi that what she has just done was because she was under the influence of an evil spirit, but Ayumi refuses to talk to her again. Azusa sadly leaves, treading the dark corridor alone.
Later, Yuuya Kizami stumbles upon Azusa, who is now wondering the halls muttering to herself. Surprised to find another survivor, Yuuya introduces himself, and offers to travel with her, claiming the living should stick together.