Okay, here's what I got from this after re-reading the ending a couple of times. If there's anything I missed, let me know.
When Kuroiwa (Yamada) came back to life after Hoshino killed him, Hoshino remembered everything from their past life and is Tsukimura Shou himself. This is evident from when he says "I'm happy we got to see each other again."
When he said "I must've been wrong about the cause of death" he meant Hoshino didn't kill him the right way, which is by strangulation, the same way Tsukimura was killed.
The reason Kuroiwa never died until now was because the final victim, Tsukimura, kept killing him the wrong way.
Both of them were cursed. Kuroiwa for being a mass murderer, and Tsukimura for being an accomplice.
After Kuroiwa was finally killed properly by Tsukimura, Tsukimura must've killed himself, thus ending their curse.
Everyone forgot about them because they finally died, ending their curse and wiping them off from the plane of existence.
Okay, here's what I got from this after re-reading the ending a couple of times. If there's anything I missed, let me know.
When Kuroiwa (Yamada) came back to life after Hoshino killed him, Hoshino remembered everything from their past life and is Tsukimura Shou himself. This is evident from when he says "I'm happy we got to see each other again."
When he said "I must've been wrong about the cause of death" he meant Hoshino didn't kill him the right way, which is by strangulation, the same way Tsukimura was killed.
The reason Kuroiwa never died until now was because the final victim, Tsukimura, kept killing him the wrong way.
Both of them were cursed. Kuroiwa for being a mass murderer, and Tsukimura for being an accomplice.
After Kuroiwa was finally killed properly by Tsukimura, Tsukimura must've killed himself, thus ending their curse.
Everyone forgot about them because they finally died, ending their curse and wiping them off from the plane of existence.