Flush toilet

1. A flush toilet comprising:

a toilet main unit that has a toilet bowl and an upper surface portion, the upper surface portion comprising an opening portion corresponding to the toilet bowl and a recessed portion; and

a functional unit that is provided on the rear side of the toilet bowl and offers a function different from a function for washing the toilet bowl,

wherein the recessed portion faces the opening portion and comprises a bottom surface that is approximately parallel with a horizontal plane, and

wherein at least a portion of the functional unit is located inside the recessed portion, and

wherein the recessed portion comprises a notch-shaped recessed portion having an open front and an open back, and

wherein the bottom surface extends rearwardly from an interior surface of the toilet bowl, and

wherein the toilet main unit has an outer circumferential wall portion that extends over an entire circumference of the toilet bowl and covers the toilet bowl from front to back and from side to side, the outer circumferential wall portion forming a space between the outer circumferential wall portion and a rear end of the recessed portion.

2. The flush toilet of claim 1 , wherein the functional unit comprises a first device, the first device offering a different function from a function for washing the toilet bowl, and wherein the first device is configured to move between an entering position, wherein a portion of the first device is located inside the recessed portion, and a retreating position, wherein the first device is located outside the recessed portion, and

wherein the functional unit comprises a second device, the second device offering a different function from a function for washing the toilet bowl, and wherein the second device is configured to move between the entering position, wherein a portion of the second device is located inside the recessed portion, and the retreating position, wherein the second device is located outside the recessed portion.

3. The flush toilet of claim 2 , wherein the first device and the second device are aligned in a lateral direction.

4. The flush toilet of claim 1 , wherein the recessed portion has a flat bottom surface.

5. The flush toilet of claim 4 , wherein the bottom surface is a flat surface comprising a length in a lateral direction that is longer than a length in a depth direction.

6. The flush toilet of claim 1 ,

wherein the recessed portion comprises two side surfaces that are each inclined so as to become closer to each other toward a lower side, and

wherein each of the two side surfaces forms an angle of 45 degrees or less with the horizontal plane.

7. The flush toilet of claim 2 , wherein the first device comprises at least one of a private part washing device, a drying device, a deodorizing device, a toilet seat heating device, and an indoor heating device, and the second device comprises at least one of a private part washing device, a drying device, a deodorizing device, a toilet seat heating device, and an indoor heating device.

8. A flush toilet comprising:

a toilet main unit that has a toilet bowl and an upper surface portion, the upper surface portion comprising an opening portion corresponding to the toilet bowl and a recessed portion; and

a functional unit that is provided on the rear side of the toilet bowl and offers a function different from a function for washing the toilet bowl,

wherein the recessed portion faces the opening portion and comprises a bottom surface that is approximately parallel with a horizontal plane, and

wherein at least a portion of the functional unit is located inside the recessed portion, and wherein the upper surface portion comprises a hollow portion inside the upper surface portion, and

wherein the hollow portion does not exist between the recessed portion and the toilet bowl.

9. A flush toilet comprising:

a toilet main unit that has a toilet bowl and an upper surface portion, the upper surface portion comprising an opening portion corresponding to the toilet bowl and a notch-shaped recessed portion; and

a functional unit that is provided on the rear side of the toilet bowl and offers a function different from a function for washing the toilet bowl,

wherein the notch-shaped recessed portion comprises an open front and an open back and faces the opening portion, and wherein at least a portion of the functional unit is located inside the recessed portion, and

wherein the upper surface portion includes a hollow portion inside the upper surface portion, and

wherein the hollow portion does not exist between the recessed portion and the toilet bowl.

10. The flush toilet of claim 1 , further comprising an elastic member that functions as a seal between the bottom surface of the recessed portion and the functional unit.