Verbal instructions via Whatsapp by Claire Ozel, Ankara, Turkey
Designer/Creator: Unknown/Traditional
If you know who the creator/designer of this model is, please feel free to let us know so that we may add a reference under this section.
Source: Diagram from an unidentified Japanese publication.
Paper to be used: 1 Square Sheet; Square, any size or color; thicker paper or thin cardstock is strongly recommended.
Folding level: Intermediate
Steps: 27
This is a fairly sturdy, long self-closing box. The lid is tucked into the front panel and folds snuggly over the base. The corners are square with 2 small triangles forming a diagonal detail.
A model folded from A4 or similar paper will make a box of around 15 x 2 x 2 cms.

Summary Explanation:
To help orient yourself, please read this section before starting to fold.
The folding of this box is divided into 4 parts:
Part 1 - Steps 1 to 12 form the Accordion Base, dividing the original square into 8 panels.
These folds may seem tedious, but they are necessary to create this type of box; so, try to perform them as accurately as possible.
If you are able to achieve this without instructions, fold the base and then go to Step 13.
Part 2 - Steps 13 to 15 - Orientation and starting folds
Part 3 - Steps 16 to 23 will create the corners and sides.
Part 4 - Steps 24 to 27 will complete the box by closing the lid over the base.
Try to focus on one part of the folding sequence at a time. This will make things easier to follow and understand.
If using two-sided origami paper, lay your paper with the patterned or colored side down before starting to fold.

Part 1 - Accordion Base
Step 1
Place a square down with its edges left and right, top and bottom.
Step 2
Valley fold the right edge over to meet the left edge. Crease and leave folded.
Step 3
Valley fold the left edge, front flap only, back to the right edge. Crease and leave folded.
Step 4
Flip the model from right to left.
Step 5
Valley fold the right edge, front flap only, back to the left edge. Crease and leave folded.
- We now have a vertical accordion fold with 4 panels.
Step 6
Valley fold the left edge, front flap only, back to the right edge. Crease and leave folded.
Step 7
Flip the model from right to left.
Step 8
Valley fold the right edge, front flap only, back to the left edge. Crease and leave folded.
- We now have a vertical rectangular shape composed of two wide inner flaps linked by a hinge fold on the right, and each carrying a narrow accordion on the left.
Step 9
Lift up the model from your folding surface. While holding the accordion fold on the left, open the fold by taking the back flap and rotating it to the right. Continue the movement all the way around until the accordion folds lie on top of each other on the left.
- The two narrow accordions are now hidden on the inside of the folded rectangle.
Step 10
Valley fold the left edge, front flap only but including the small accordion panel,  back to the right edge. Crease and leave folded.
- You should now have a rectangle divided down its center, with the right side being slightly thicker than the left.
Step 11
Flip the model from left to right.
Step 12
Valley fold the right edge, front flap only but including the narrow accordion panel,  back to the left edge. Crease and leave folded.
- You should end up with a long, skinny strip or an eight-fold accordion.

Part 2 - Orientation and starting folds
Step 13
Open the paper completely and place it down with the creases running vertically or from top to bottom.
It is important to keep your square in this orientation for the next steps.
You will notice that you have a square divided into 8 long panels.
Another way of looking at the square is that it has 7 alternating vertical valley and mountain crease lines across it.
Keep in mind that the left side of the square will become the lid of your long box while the base will be formed on the righthand side. The corner folds will be made along the top and bottom of your square.
To close the box you will be folding over the lid from left to right.
Mentally number the panels on your square from 1 on the left to 8 on the right.
Step 14
Fold Panel 1, on the left edge, over so it lies on top of Panel 2.
Step 15
Fold Panels 7 and 8, on the right edge, over so they lie on top of Panels 5 and 6.
Put in another way, your fold line should be between panels 6 and 7, so that Panel 8 is on top of Panel 5 and Panel 7 is on top of Panel 6.
You will now have a rectangle with the edges folded towards the center and made up of 5 vertical panels.
Looking at these 5 panels, Panels 1, 4 and 5 will be two layers thick while at the center of the rectangle, Panels 2 and 3 will only be single-layered panels.
We will refer to these 5 panels for the next steps, with 1 being the panel on the left and 5 on the right.

Part 3 - Sides and corners
Step 16
Focus on the right edge of the square first, working with panel 5.
Fold both layers of the top and bottom corners inwards to meet the first vertical crease you encounter.
These folds are diagonal folds at 45 degrees and will form small corners on the far right, top and bottom of the square.
They will cover Panel 5, the panel along the right edge of the square.
Step 17
Locate Panel 4 and fold 2 similar corners, one at the top and one at the bottom, but in the opposite direction of those folded in the previous step.
These folds will also be made diagonally, at a 45 degree angle and will cover panel 4, but only one layer will be involved now.
The right edge of the square, consisting of panels 4 and 5, will now have slanted corners and the folds will look like arrows, one pointing up and another pointing down.
Step 18
Fold Panel 4 over so it comes to rest on top of Panel 5. The right edge of the square will now consist of a 3-layered panel.
Step 19
Now focus on the left side of the square, where you will still have Panel 1 folded on top of Panel 2.
Fold the top and bottom corners over diagonally so they  also cover Panel 3. Their edges should lie along the fold line between Panels 3 and 4.
These corners will be similar to,  but larger than those you have formed on the right of the model.
Crease well and leave folded.
Step 20
Using the corners you folded on the right, for panels 4 and 5, as guides, fold the entire top and bottom edges of the square up and down.
When you fold these edges, the corners on the right will fold over on themselves, while the corners on the left will basically fold in half, creating new creases.
Make sure you fold as straight as possible here, since you won't have a clear edge as a guide.
Leave folded.
You will now have folded fairly short bands on the top and bottom with slanting sides that are lying on top of the corner folds you have already made.
Step 21
Next, we will create small diagonal folds, by folding the bands over on themselves.
This is a kind of shifting fold, since you will basically fold the flat band on top of itself  to form the hinge of your box.
So, working with the short band nearest you, find the vertical crease that divides panels 3 and 4.
Holding the paper down with your right forefinger just to the right of the vertical crease you have identified, valley fold the top edge of the band diagonally down or towards you, so it meets the vertical line you encounter.  Crease the fold, which will run from top right down to the bottom left.
A small triangle will form, covering half of panel 3, which will have the effect of bringing panels 1 and 2 into an upright position. Make a strong crease so that this triangle will lie completely flat.
Step 22
Still working with the edge nearest you, hold down the triangle you just folded on the left and make a similar, but opposite fold on the right of the vertical line between panels 3 and 4.
Another small triangle will form, covering half of panel 4, which will have the effect of bringing panel 5 into an upright position. Once again, make a strong crease so that this triangle will also lie completely flat
The edge nearest you will now have a flat triangular structure, made up of 2 folded triangles pointing away from you, each covering half of Panels 3 and 4.
Make sure this triangular structure lies flat toward the inside of the box for the remaining steps.
Step 23
Turn the square 180 degrees and repeat Steps 21 and 22 on this side as well.
You will once again have the two triangles next to each other, covering Panels 3 and 4. Remember to press them flat to the inside of the box.

Part 4 - Closing the lid
Step 24
Turn the model to the right, so the short edges are now left and right and the front is nearest you. Bring the front into an upright position by pressing it away from you. At the same time, press the corners just behind the front panel inwards so they will form a 90 degree angle with the front panel.
If there are still folds along the short sides that seem to bulge toward the outside of the box, press them to the inside again.
You can let the lid lie flat at this point.
Before attempting to close your box, first check that you have folded the following parts correctly:
Mentally number the long panels of the box again, with the front panel as panel 1, moving away from you to panel 5, which is the part of the lid that will tuck into the front panel.
Panel 1, Nearest you, has 3 layers. First, a closed fold of 2 layers and just behind this, a single layer with a raw edge.
Panel 2 should be the bottom of the box, a single layer which is flat on the table.
Panel 3 is the back panel of the box, another single layer.
Panel 4 is also a single layer, which will form the top of the box.
Panel 5 is a double layer with 2 sloping corners, which will allow it to slide into the front opening of the box.
You will also need to check each short side of the box to ensure that the corners have been formed correctly. 
To do this, start nearest you and slide a finger on both sides of the box, moving as indicated until you reach the lid at the back.
On each short side of the box, just behind the front panel, you will find a small 4-layered triangle that should be perpendicular to your front panel.
Mentally label this structure as Triangle A. If you follow this triangle downwards you will find 2 triangles that should be lying flat toward the inside of the box (Triangle B), and then, moving still further away from you, another side triangle (Triangle C) that will lay in the same orientation as Triangle A.
 Follow this triangle upwards until you reach the point where the model makes a turn inwards.
 This quite large triangle leads upwards into the flat edge of the lid.
To close the box, the slanted front part of the lid or "tab" will fit inside the front panel, just behind the single-layered raw edge described earlier.
When closing your box, make sure that Triangle B folds flat inside the box and then that  Triangle C folds over Triangle A on both sides of the box.
Put in another way, for the sides of the box to form properly, the 2 triangles near the back should be on the outside of the box, covering the triangles near the front.
The structure described as Triangle B should disappear inside the box and should lie completely flat to make space for the other 2 triangles to meet.
In this way, everything has a space to fit into. 
Step 25
Start to close the box by bringing the edge furthest away from you upright and towards you until it folds over the front edge.
The edge of the lid is sloped on the left and right sides, so that it can fit into the slot on the front of the box.
It will help if you first just bring the lid so it lies on the outside front of the box. Gently hold it in place while you investigate the rest of the box, including the corners.
The small back corners (Triangle C) should fold over the small triangular front corners (Triangle A) when the box is closed.
Step 26
Tuck the edge of the lid into the slot that you will find at the front edge of the box.
Step 27
Check and reinforce the corners if necessary and ensure that all sides and edges are crisp and neat.
Make sure your folds are similar on the left and right of the box. If these folds are somewhat off, it will prevent your box from closing properly and the side corners, which should be made up of a diagonal fold, might not form correctly.
If folded correctly, the little side corners will slope from the top front downwards to the back and the box will stay closed. If it keeps wanting to open, it is likely that the corners and the inside structure are not lined up properly, which will prevent the parts of the box to fall properly into place.
It might take you a few tries to get this box folded, but it is totally worth it!