There are several endings within Corpse Party: Seal ~Eternal Cycle~. Two of the endings are based on the endings from the chapter "Seal" from Corpse Party: Book of Shadows, while the other four are new endings created for the game.
Requirements: Get caught by Yoshie in classroom 3-A.
Naomi is killed by Yoshie while trapped in classroom 3-A.
Requirements: Try to force the lever outside the 2F-3F East stairwell without using the key.
Naomi tries to force the lever controlling the bridge to the stairwell. After the bridge extends, a thread of sharpened wire moves across the hallway and slices Naomi in half.
Requirements: Do not apologize to Seiko. Remain with Seiko in the custodian's closet.
Naomi is overtaken by the darkening after hearing Seiko's confession, killing her in a fit of rage.
Requirements: When Seiko is being hung, leave to get the bucket or try to grab her three times.
Naomi is unable to save Seiko from hanging to death and loses hope. This ending is based on endings 1*2 and 1*3 from Book of Shadows.
Requirements: Complete the game without getting another ending. If the option is presented, choose to stay with Seiko after saving her in the bathroom.
Naomi saves Seiko from hanging to death. However, Seiko runs from Naomi as soon as she comes to. Seiko is unaware of the sharpened wire on the stairwell, and decapitates herself while trying to flee from Naomi. Sachiko mocks Naomi for trying to change Seiko's fate before preparing Naomi for the next cycle. This ending is based on ending 1*1 from Book of Shadows.
Requirements: Apologize to Seiko. Remain with Seiko in the custodian's closet. Leave Seiko behind in the bathroom.
Naomi saves Seiko from hanging to death, but chooses to distance herself from Seiko. As she is leaving, Seiko wakes up and chases after her. Seiko stabs Naomi with a shard to glass, causing Naomi to bleed to death. Sachiko appears to mock Seiko, amused that there was a new outcome in this cycle. Sachiko then prepares Seiko for the next cycle.