There are only certain bloodsucking points on each of the people in each level: 

1)rena's room: right leg(you do best when you turn off the lights three times first,
she will see you less) 

2)storage room: you can bite her on her left leg, but only while she is on the left
side of the room, distracted with a book. 

3)living room: on his head, but only after he has gotten up to look at the chime
after you ring it, turn off the tv with the remote, or turn on the phone. 

4)bathroom: this one's tough. it's very foggy in here because rena's taking a very
warm bath. there are bubbles in the air, so try to watch out. she may hear you pop
them and look up. this one also has a time limit of 3mins 20secs. i found it useful
to wait until she was totally tranquil(green radar @bottom left corner) and then i
went up and bit her. that way i got almost if not an entire tank off of one bite but
after one tank TAKE OFF or else she will slap you and you will die(obviously). you
can't get any when she is drifting to sleep. so watch. you will see the red square
and it will disappear when she begins to drift off. 

5)kitchen: on the bottom of her left foot or on the pinky toe of her right foot.
only when she is away from the stove. same green policy applies, though sumtimes i
caught an unsuspected slap. 

6)rena's room(again!): this time she is practicing her karate. if you make her phone
ring(it's on her bed) she will answer it. at that time you must be very quick and
either bite the finger on the hand that isn't holding the phone or just under her
hair on the left side of her neck. same green policy applies. 

Submitted by Twerpster5