The rare/hard-to-find item info has been taken from slo_bro's faq over at game faq's with his permission. I did not write this, I'm merely expanding the reach of this info. Enjoy.
These are in alphabetical order. If there's an item you need that isn't on the list, feel free to contact me and I'll do my best to help you out. Note that some items are grouped together(food menus, etc).
100 points! Level: Shimano House - 25cm0mm How To Find: on the wall behind the boy's bed
Air Freshener Level: Sweets Stage - 21cm0mm How To Find: You can see its round orange cover sticking out of the ground outside by the turtle.
Bamboo Level: Age Stage - 7m43cm0mm How To Find: on a hill with lots of other stuff
Bathroom Scales Level: Oak Town - 42cm3mm How To Find: Go past the back door of the restaurant you can enter and turn left.
Baumkuchen Cake Level: Sweets Stage - 39cm2mm How To Find: Girls are throwing it upstairs.
Bento Lunch Level: Sakura Town - 27cm1mm How To Find: by the benches above the pool, where all the dolls are walking
Bookstand Level: Sakura Town - 42cm2mm How To Find: down by the pool with books in it
Cafe Oak Menu - Maple Town - 1m90cm0mm Chinese Menu - Sakura Town - 1m47cm0mm Lunch Menu - Maple Town - 1m71cm0mm Model Lunch Set - Maple Town - 1m80cm0mm Model Lunch Set - Oak Town - 1m86cm0mm Set Lunch Menu - Oak Town - 1m52cm0mm Yam Cha Menu - Sakura Town - 1m13cm0mm How To Find: sitting in front of the entrance to the restaurant you can enter
Cake Shop Sign Level: Oak Town - 1m33cm0mm How To Find: in front of a building you reach by turning left past the 75cm barrier
Canned Peach Level: Sweets Stage - 36cm9mm How To Find: on the bed upstairs
Cart Level: Sakura Town - 65cm3mm How To Find: A Paper Tiger is pulling it on the steps above the pool.
Cat Monster Level: Sakura Town - 79cm6mm How To Find: doing laps around the shrine (past the 75cm barrier and up the steps)
Chinese Lantern Level: Zucchini Land - 89cm2mm How To Find: attached to buildings on the square hill you climb by going up a waterfall
Clay Stove Level: Maple Town - 68cm5mm How To Find: Fish are sitting on them next to the pool.
Clock Tower Level: Age Stage - 5m1cm0mm How To Find: on a raised spot near where you start
co - File Select Screen - 10cm9mm m - File Select Screen - 9cm1mm na - File Select Screen - 10cm5mm Registered Trademark - File Select Screen - 2cm3mm How To Find: Roll up the desired thingy, choose "No," then start your game and save.
Compass Level: Model Shop - 7cm3mm How To Find: There is a row of them at the edge of a table.
Cookie Tin Level: Sweets Stage - 29cm5mm How To Find: Go upstairs, go outside, climb the ramp, jump down.
Cowshed Level: Potato Land - 15m52cm0mm How To Find: back in the area made like a 1.5m-10m town, before the 30m barrier
Crane Scaffold Level: Rocket Stage - 34m81cm0mm How To Find: The huge crane is sitting on it.
Cucumber Plant Level: Chameleon Stage - 75cm0mm How To Find: the plants fruit are hanging from, get while between 75cm and 80cm
Deer Level: Age Stage - 1m3cm0mm How To Find: on a low plateau of a hill far from where you start
Demon Granny Level: Strawberry City - 1m97cm0mm How To Find: across a bridge from the big building
Disinfectant Level: Model Shop - 7cm3mm How To Find: on the floor near one of the piles of coins
Drag Racer Level: Radish Land - 7m85cm0mm How To Find: doing laps on the hill, before the 30m barrier
Drainboard Level: Maple Town - 42cm0mm How To Find: in front of the fenced-in building, behind Towel Guys, before the 20cm barrier
Drawer Level: Strawberry City - 58cm7mm How To Find: sticking out of a cabinet right in front of the big building
Drugstore Sign Level: Oak Town - 1m35cm0mm How To Find: in front of a building you reach by turning right past the 75cm barrier
Eggplant Level: Sakura Town - 85cm3mm How To Find: A row of them is around the corner of a building, past the 75cm barrier
Eiichi Nonoshita Level: Oak Town - 1m78cm0mm How To Find: sitting on an elephant, past the 75cm barrier
Fairy Tale Book Level: Shimano House - 25cm0mm
on the floor in the girl's room
Fukinagashi - Strawberry City - 4m18cm0mm Higoi - Strawberry City - 3m31cm0mm Kogoi - Strawberry City - 2m86cm0mm How To Find: A row of these are swimming just beyond the 4m barrier on water
Globe Level: Sweets Stage - 61cm0mm How To Find: get really big and go upstairs
Goldfish in a Bag Level: Sakura Town - 37cm1mm How To Find: catch the rows of jumping fish
Gratin Level: Oak Town - 26cm5mm How To Find: ?
Hyottoko Mask Level: Chameleon Stage - 38cm7mm How To Find: on shelves with lots of little stuff under a canopy, beyond the 80cm barrier
Icicle Level: Maple Town - 11cm6mm How To Find: hanging from the gate up the stairs past the 75cm barrier
Jack-In-A-Box Level: Sakura Town - 41cm9mm How To Find: Bump a tree by a drunk above the pool.
Kid's Boot Level: Sakura Town - 40cm8mm How To Find: next to the pool
Konosuke Kubo Level: Oak Town - 1m16cm0mm How To Find: doing laps around the shrine, past the 75cm barrier and up the steps
Lamp Ghost Level: Sakura Town - 1m55cm0mm How To Find: Bump a tree to the right as you go through the 75cm barrier.
Lantern Level: Maple Town - 61cm8mm How To Find: Bump the pole with snow at its base near the restaurant's front door you can enter, and a Burglar holding a Lantern will fall.
Laundry Deck - Oak Town - 1m48cm0mm Laundry Hanger - Oak Town - 1m42cm0mm How To Find: in an alley far to your right as you pass the 75cm barrier
LED Light Level: Sakura Town - 22cm9mm How To Find: between two parked cars and a big building, before the 75cm barrier
Light Bulb Level: Sakura Town - 20cm5mm How To Find: among eggs and ducklings just past the car
Lion Fountain Level: Age Stage - 9m13cm0mm How To Find: ALSO IN POTATO LAND up at the top of the river before the 30m barrier
Lovely Mascot Level: Shimano House - 8cm1mm How To Find: a Teddy Bear (pig-like animal) is guarding it in the girl's room
Magazine Level: Sakura Town - 29cm4mm How To Find: among the book stands next to the pool
Mahjong Tile Level: Joushima Villa - 4cm9mm How To Find: This one is in the little hallway between rooms, by a plate of parsley.
Megaphone Level: Oak Town - 46cm1mm How To Find: People on trucks are holding them.
New Year's Envelope Level: Maple Town - 10cm2mm How To Find: in a wall of bricks past the back entrance of the restaurant
Pampas Grass Level: Sweets Stage - 46cm3mm How To Find: outside
Panda Mascot Level: Sweets Stage - 60cm0mm How To Find: halfway up the stairs
Parking Turntable Level: Melon City - 8m64cm0mm How To Find: along the raised road behind the ski-lift hill
Part-Timer Level: Oak Town - 1m83cm0mm How To Find: in front of a store near desks and chairs, past the 75cm barrier
Picnic Mat Level: Oak Town - 1m30cm0mm How To Find: right next to where you start, next to a kneeling Grandma
Portrait Level: Chameleon Stage - 39cm3mm How To Find: kids are sitting with artwork next to a kid on a scale holding a watermelon
Public Bath Level: Radish Land - 27m85cm0mm How To Find: on the square hill you climb a waterfall to reach before 30m barrier,squeeze up the waterfall at around 25-26m
Pumps Level: Maple Town - 32cm8mm How To Find: in a shoe store display against a building beyond the 75cm barrier
Rabbit Level: Sweets Stage - 51cm8mm How To Find: upstairs
Relaxing Boy Level: Chameleon Stage - 1m42cm0mm How To Find: sitting in front of the restaurant
Restaurant Curtain Level: Oak Town - 1m2cm0mm How To Find: hanging from the restaurant's front door
Rubber Boot Level: Sweets Stage - 58cm6mm How To Find: Get big, then go outside.
Security Guard Level: Sakura Town - 1m63cm0mm How To Find: standing in front of the big building with parked cars, before the 75cm barrier
Shortcake Level: Sweets Stage - 45cm0mm How To Find: big cake slices on the table where you start the stage
Slingshot Level: Maple Town - 23cm9mm How To Find: A kid is holding it by the restaurant door.
Sneaker Level: Oak Town - 36cm1mm How To Find: just before you reach the 75cm barrier, on the right side of the road
Steel Cover Level: Sweets Stage - 56cm9mm How To Find: It's a ramp for little katamaris trying to get in from outside.
Store Sign Level: Maple Town - 1m80cm0mm How To Find: hanging from a building you reach by turning right past the 75cm barrier
Strawberry Pack Level: Sweets Stage - 27cm4mm How To Find: in the refrigerator
Straw Hat Level: Sweets Stage - 44cm9mm How To Find: on the back of the sofa
Telephone Pole Ad Level: Sakura Town - 84cm2mm How To Find: Bump the pole far to your left as you cross the 75cm barrier.
Telephone Pole Brace Level: Sakura Town - 1m23cm0mm How To Find: leaning on the side of the pole far to your left as you cross the 75cm barrier
Teruterubozu Level: Chameleon Stage - 30cm1mm How To Find: hanging from the benches way above the pool
The Prince Level: Tutorial How To Find: play the Tutorial level as June
Thick Chopping Board Level: Sakura Town - 59cm8mm How To Find: in the restaurant, on a back part of the counter
V1 Level: Potato Land - 96m79cm0mm How To Find: taking off and landing at the runway past the 30m barrier
Ventilation Fan Level: Sakura Town - 50cm8mm How To Find: A row of them are along the side of a street before the 75cm barrier.
Video Game Level: Sweets Stage - 38cm2mm How To Find: up high upstairs
Well Pump Level: Banana City - 1m83cm0mm How To Find: behind two tents before the 4m barrier
Wild Cactus Level: Zucchini Land - 18m92cm0mm How To Find: There is a row of them in the hole in the ice.
Windchime Level: Model Shop - 20cm2mm How To Find: Ride the Shogi Board lifted by pigeons only halfway up.
Young Monk Level: Sakura Town - 1m41cm0mm How To Find: one of the people behind the back row of food stands