Take coffee tin from above pink sofa.
Open tin and take hint note (GRATITUDE).
Examine glass-box lamp above sofa to see it’s screwed in place.
Look under table. Notice pattern on rug. Take donut from behind table.

Examine red shelf (the one made of three red boxes).
In the top compartment, there’s a box with a symbol lock.
In the bottom compartments, there are two round creatures (mochis according to manami?).
Notice their facial expressions. Look under right mochi and note down number.
Return to box in top compartment. Enter the symbols that show the eye shapes of both mochis, from left to right. Take key from box.

Go to view with white door.
Look at left plant and take pencil-llike thing from flower pot. Examine it and take off cap to see that it’s actually a cutter.
Examine square shelf with 9 compartments. Take donut and note that there are differing numbers of cookies in 4 compartments.
Examine pink machine. It has openings into which 4 donuts fit. Looks like you need more donuts!

Go to view with window in wall.
Examine the stair-like podium with three mochis. You have already found one of these mochis in the room and will need to look for the others to get the password.
Examine the various doors and drawers. You cannot do much here at this moment.

Go to view with grey door.
Examine brown shelf of stacked boxes. There is a square hole in one compartment.
Look at door. You can peek through the windows and see a bathroom.
Look at red mochi. Note down the number below it.
Examine illuminated red letters. Use this hint combined with the note from the coffee tin to open the locked drawer in the white-and-pink cupboard (view with window):

The note says GRATITUDE, and the illuminated letters say
IDEA
GRUT
That’s two rows, and four letters in each. The drawer also has two rows of four buttons each.
Press the corresponding buttons to spell out GRATITUDE.

Take folded pink stool. Fold stool.
Place stool under window. Examine windowsill.
Take donut from strawberry bowl.

Back to the white/pink cupboard. Unlock left door with key.
Take donut and white board with cut-out holes. Examine board and note the hint that it’s for the stacked-boxes brown shelf.

Go to pink machine and insert all donuts into holes. Press white button.
Take lighting remote control.

Go to view with grey door. Use white board with holes with shelf.
Note down the numbers you see in the holes. In case you’re not sure about the numbers, they are

9346

Use these numbers to open second door in white/pink cupboard. Take screwdriver.
Go to sofa and look at glass-box lamp above it. Unscrew lamp.
Notice that lamp had been in a square hole. Go to shelf next to grey door.
Insert lamp into square hole.
Left of the shelf, a square in the wall becomes visible (it’s a bit lower than the rest of the wall). Use cutter on square. Press button.

At grey door, look through window and use lighting remote control.
Note down the directions of the arrows.
Press the corresponding arrow buttons next to the door.
Enter bathroom.
Look at tub and notice it’s empty.
Take white box from behind tub. Notice the locking mechanism of the box (numbers with number fields below it).
Look at control panel in the left wall. There are buttons that show symbols and a square matrix with 9 compartments.
The hints for this control panel are the carpet and the shelf with the cookies in the other room – use them to open it.

Further hint: The carpet shows nine fields with various symbols.
The shelf shows which field to choose and in which order to enter them.

Still need more help?
First symbol is the field on the carpet for which there is one cookie in the shelf, second the one with two cookies etc.

The tub fills with water. Look at the tub and examine the mochi. Note down the number at its “belly”.
You now have all the hints to open the podium on the white/pink cupboard.

You need to enter the number for each mochi in the field at the bottom of the podium. Enter the numbers in the order of mochis as given on the podium (i.e., the guy in the middle’s number goes first, then the one on its right, then the one on its left).

Click drawer to open it. Take paper with puzzle.
This is the final hint for the white box from the bathroom. It’s a game called “ghost leg” and works like this:
Choose a number and follow the line below it. Whenever there is a lateral branch in the line, you must follow the branch, then continue on the next line.
This and the yellow field that’s both on the white box and the paper is you need to know to find the code.

So here’s some more help:
The box tells you to use the numbers that result from following lines 6, 7 and 1. Therefore, follow these lines. The numbers are those lines you follow when you are within the yellow field.
If that’s still not clear enough, code’s in the next spoiler.

512

Enter code in white box, take key and unlock white door.