Here we go:
One day the watchman at the Towa cementary was on guard duty, his job was to make sure no one vandalised the graves and if they were to come back to life, to make sure that they wouldn't suffocate down there.
One day he heard a large ring of a bell coming from the Tombstone of Kaori Miyazono.
When a bell rings, it indicates that they are still alive and are waiting to become unburied.
The watchman grabbed a shovel and dug up the coffin which Kaori laid and then opened it to find Kaori with her eyes open and shivering, it was a cold night, after all it had been 2 months since she was buried and it was May, exactly 1 year and 1 month after she met Kōusei.
Immediatly afterwards the watchman called the hospital and Kaori was taken to the hospital.
A few hours later
The doctor in the hospital decided to give Kaoris parents a call that would change everything
Kaoris parents had been running Ma Fille Bakery for the past few months, they had managed to move on from their daughter as she was gone and now they were fully focused on trying to keep the bakery in full order.
Until they received a call at 2AM
"Hello" said Yoshiyuki
"Hello this is the hospital, I need to tell you urgent news" said the doctor
"What is it" said Yoshiyuki
"Well you see your daughter woke up in her coffin and now she was transported to the hospital, you and your wife can visit her anytime you want, she is in the same room as she was when she was last here" said the doctor
"Okay, we will be there right away" said Yoshiyuki
"Good, good, see you there" said the doctor hanging up
"Who was that" said Ryouko
"Well that was the hospital, apprantly our daughter has just woken up in her coffin and is now currently recurring treatment in the hospital" said Yoshiyuki
"Wait what" said Ryouko
"Am I insane" said Yoshiyuki
"No dear your not, we will go see if it's true and if it is, I would love to see her again" said Yoshiyuki
Afterwards both of them got changed and set off and on the way Yoshiyuki messaged Kōusei Arima
"Hello Kōusei, this is Mr Miyazono, meet us at the hospital immediately, Apprantly Kaori has woken up from her coffin and is now in the hospital receiving medical treatment"
Kōusei was woken up when he saw the text and was surprised that it was from Kaoris dad and then he read it, he first felt total disbelief, he saw Kaoris corpse, the dead don't exactly come back. however Kōuseis curiosity and love for Kaori led him to get changed and sneak outside to the hospital which luckily neither Hiroko or Tsubaki spotted him.