Buckle

1. A buckle, comprising:

a male member including a pair of arms each having an engaged part near a front end; and

a hollow female member including, at one end of the hollow female member, an insertion port into which the pair of arms is inserted, and an engaging part, at the other end of the hollow female member, engaging the pair of arms with the engaged parts,

wherein the female member includes a first side wall and a second side wall, extending in a flattened direction and being opposed to each other, an opened port opposed to the insertion port at the other end of the hollow female member, a belt attachment part situated away from the opened port, and an opening located between the belt attachment part and the opened port and directly facing the opened port and communicating therewith;

the first side wall is shaped such that the pair of arms is not exposed from an edge of the opened port defined by the first side wall in a state where the engaging part is engaged with the engaged parts, when viewed from a plane opposed to an outer surface of the first side wall;

the second side wall is shaped such that at least one of the pair of arms is exposed from the opened port defined by the second side wall in the state where the engaging part is engaged with the engaged parts, when viewed from a plane opposed to an outer surface of the second side wall; and

the female member is hollow throughout an entire length thereof from the insertion port to the opened port.

2. The buckle according to claim 1 , wherein in the opened port, an edge of the second side wall is more recessed toward the insertion port than the edge of the first side wall when viewed from the plane opposed to the outer surface of the second side wall.

3. The buckle according to claim 2 , wherein

the first side wall has a first opening edge constituting the edge of the opened port; and

the second side wall has a second opening edge as the engaging part constituting the edge of the opened port, which is more recessed toward the insertion port than the first opening edge when viewed from the plane opposed to the outer surface of the second side wall, and is shaped such that the engaged parts are exposed from the second opening edge in the state where the engaging part is engaged with the engaged parts, when viewed from the plane opposed to the outer surface of the second side wall.

4. The buckle according to claim 3 , wherein

the engaged parts are second engaged protrusions protruding toward the second side wall in the pair of arms, and

a width of the second engaged protrusions in a thickness direction of the second side wall is smaller than a thickness of the second side wall.

5. The buckle according to claim 4 , wherein

the male member further includes first engaged protrusions protruding toward the first side wall in the pair of arms, and is shaped to be symmetric about a plane including the pair of arms; and

the female member has a guide groove that extends from the insertion port to the opened port, and guides the engaged parts between the insertion port and the opened port.

6. The buckle according to claim 5 , wherein

the insertion port has a front side insertion edge on the first side wall and a back side insertion edge on the second side wall,

the first side wall has the edge of the first side wall at an end part of the opened port on the first side wall,

the second side wall has the edge of the second side wall at the end part on a side opposite to the insertion port, and

a length from the front side insertion edge to the edge of the first side wall is longer than a length from the back side insertion edge to the edge of the second side wall.

7. The buckle according to claim 6 , wherein the second engaged protrusions engage with the edge of the second side wall when the male member and the female member are engaged.

8. The buckle according to claim 2 , wherein

the insertion port has a front side insertion edge on the first side wall and a back side insertion edge on the second side wall,

the first side wall has the edge of the first side wall at an end part of the opened port on the first side wall,

the second side wall has the edge of the second side wall at the end part on a side opposite to the insertion port, and

a length from the front side insertion edge to the edge of the first side wall is longer than a length from the back side insertion edge to the edge of the second side wall.

9. The buckle according to claim 1 , wherein the opened port entirely faces the belt attachment part directly through the opening.

10. A buckle, comprising:

a male member including a pair of arms each having an engaged part near a front end; and

a hollow female member including, at one end of the hollow female member, an insertion port into which the pair of arms is inserted, and an engaging part, at the other end of the hollow female member, engaging the pair of arms with the engaged parts,

wherein the male member further includes

bottom end positioning ribs at bottom ends on a front surface and a back surface of the pair of arms, and

front end positioning ribs at front ends on the front surface and the back surface of the pair of arms,

the female member includes a first side wall and a second side wall, extending in a flattened direction and being opposed to each other, an opened port opposed to the insertion port at the other end of the hollow female member, a belt attachment part situated away from the opened port, and an opening located between the belt attachment part and the opened port and directly facing the opened port and communicating therewith,

the first side wall is shaped such that the pair of arms is not exposed from an edge of the opened port defined by the first side wall in a state where the engaging part is engaged with the engaged parts, when viewed from a plane opposed to an outer surface of the first side wall,

the second side wall is shaped such that at least one of the pair of arms is exposed from the opened port defined by the second side wall in the state where the engaging part is engaged with the engaged parts, when viewed from a plane opposed to an outer surface of the second side wall, and

the female member is hollow throughout an entire length thereof from the insertion port to the opened port.

11. The buckle according to claim 10 , wherein the opened port entirely faces the belt attachment part directly through the opening.