context: Master Kow [Ching-Ying Lam] runs the local mortuary and is an expert on vampires and
  ghosts. He and his two bumbling assistants, Man Chor [Ricky Hui] and Chou [Chin Siu-hou], have the
  responsibilities of performing funerary rituals and carrying for the
  bodies of the dead, which includes the eight chiang-shih (hopping
  vampires) who, along with the Taoist priest who controls them by ringing a
  bell, are Master Kow's guests. That evening, as Man Chor is checking the
  wards pasted on the foreheads of the chiang-shih, lighting the incense
  which feeds them, and making sure that the flame which holds them
  motionless does not burn out, the joke-playing Chou startles Man by
  jumping out of a casket wearing a walking corpse* costume. While trying to
  save himself, Man stumbles against the altar, extinguishing the flame.
  Immediately, the wards start falling from the foreheads of the
  chiang-shih, and they start hopping around. Fortunately, Master Kow and
  the priest are able to secure them again, but the priest and his
  chiang-shih decide to stay elsewhere.The next day, Master Kow and Man meet Mr Yam for coffee. Mr Yam wants
  to talk to them about digging up and reburying his dead father, because he
  was told by a fortune-teller that it will bring him good luck. While Mr
  Yam and the Master discuss the process, Man has become enamoured of Mr
  Yam's daughter Ting Ting [Choi-fung Li], who has just returned from the city where she
  has been studying cosmetics. Three days later, everyone gathers at
  Grandfather Yam's grave for the disinterment. Master Kow tells Yam that
  the ground is contaminated and that they must bury Grandfather Yam
  elsewhere. He offers to take the body to his mortuary where it can be kept
  until another spot is found. To ease the spirits of the other bodies
  buried there, Man and Chou are told to place incense on each grave. One of
  the graves catches Chou's eye. It is the grave of a young girl named Jade.Later that evening, when the Master looks at Grandfather Yam's body,
  he notices that his skin is changing and his fingernails are long and
  blue, signs that he's turning into a vampire. Master Kow prepares a magic
  ink which must be painted at right angles all along the coffin, forming a
  grid which will help to keep the body from getting free. Unfortunaely, it
  doesn't work, and Grandfather Yam [Wah Yuen], now a chiang-shih, escapes during the
  night. The first place he hops is over to Yam's house, where he kills his
  son. Wai [Billy Lau], the bungling captain of police who also has the hots for Ting
  Ting, blames the murder on Master Kow because of his long fingernails and
  arrests him. Kow warns Man and Chou that Yam will rise as a corpse, too,
  and bids Man to protect Ting Ting while Chou is to bring him an inkpot and
  some sticky rice and meet him at the jail. Just as Chou is delivering the
  sticky rice (which, unfortunately, he cooked instead of bringing it raw),
  Yam awakens. After a bit of kung-fooy, during which Wai gets the worst of
  it, Master Kow and Chou manage to stake Yam and set his body on fire. One
  vampire down, but Grandfather Yam is still out there.Meanwhile, Grandfather Yam has returned to Yam's house where he
  chases around Man and Ting Ting for a while. Fortunately, they know that,
  if you hold your breath, a chiang-shih can't see you, so they manage to
  elude him until Master Kow, Chou, Wai, and the police show up. In the
  melee that follows, Man is bitten by Grandfather Yam, who gets away. Now
  they've got another problem on their hands in that Man could turn into a
  vampire, too. The only thing to do is to keep Man moving so that his blood
  doesn't turn stiff and to send Chou after some more sticky rice to draw
  out the poison.But Chou has his own problem. Jade [Siu-fung Wong], the girl whose grave Chou saw
  when they were digging up Grandfather Yam's body, has fallen in love with
  Chou and come back as a succubus ("Lady ghost") to make love to him. She
  forces the night watchman to flirt with her, then screams for help just as
  Chou is riding by with the sack of rice on his bicycle. He rescues her and
  takes her to her home. When a sudden thunderstorm sends down torrents of
  rain, she convinces him to stay the night. The next morning, when Chou
  returns, Master Kow notices the love marks on his neck and surmises that
  Chou has slept with a ghost. Chou sleeps away the day. When he wakes up,
  he heads right back to Jade's house. Master Kow follows him, where he
  fights with the succubus (who does some interesting things with her head)
  until she flies away.Later that night, after tying up Chou, the Master waits on the front
  porch for Jade to come. When she does, he does magical battle with her.
  Meanwhile, inside the house, Man has awakened from sleep and found that
  he's transformed into a vampire (of the walking corpse type). He tries to
  bite Chou, but Jade saves him. Chou begs Kow not to harm Jade, so he
  washes his hands of their love affair and reminds them only that they are
  from two different worlds. With tears in her eyes, Jade flies away. Now
  the question is why the sticky rice didn't prevent Man from turning into a
  vampire. Master Kow takes a hard look at the stuff and finds that it's
  been cut with regular rice. He sets Ting Ting to work sorting the grains,
  while Chou files down Man's fangs.Suddenly Wai and his men burst in the door. Grandfather Yam is on the
  move again. Man, Chou, and Ting Ting spread sticky rice all around the
  house, then barricade the doors and windows. But they forgot the skylight.
  Grandfather Yam, now looking more like a walking corpse, breaks in through
  the skylight and takes them all on. Suddenly, the Taoist priest and his
  eight chiang-shih pay a visit. When the priest sees what's going on, he
  leads his vampires into the house and commands them to surround
  Grandfather Yam. But Grandfather Yam is one strong corpse and knocks out
  all the chiang-shih. At some point, the priest drops a ceiling lantern on
  Grandfather Yam. He bursts into flames as do the chiang-shih.*Both the chiang-shih and the walking corpses appear to be vampires, but
  the chiang-shih hop and are controllable by the Taoist priest while the
  walking corpses lumber along more like ghouls and are difficult to stop.
  [Original Synopsis by bj_kuehl.]
question: Who restores Choi's health and turns him back into a human?
answer: Kau