Golf club and golf club set

1. A golf club comprising:

a shaft;

a head attached to a tip part of the shaft; and

a grip attached to a rear end part of the shaft,

wherein:

the head includes a sole surface and a face surface having a face line;

the sole surface includes a ridgeline extending from a toe side toward a heel side, a leading surface positioned on a face side of the ridgeline and inclined upward toward the face side, and a trailing surface positioned on a back side of the ridgeline and inclined upward toward the back side; and

if an inclination angle of the trailing surface is defined as θ 2 ; the inclination angle θ 2 at a central position of the face line is defined as θ 2 c ; the inclination angle θ 2 at a toe reference position is defined as θ 2 t ; and the inclination angle θ 2 at a heel reference position is defined as θ 2 h,

the golf club satisfies at least one of the following (a) and (b):

(a) the inclination angle θ 2 t is greater than the inclination angle θ 2 c;

(b) the inclination angle θ 2 h is greater than the inclination angle θ 2 c.

2. The golf club according to claim 1 , wherein the golf club satisfies both the following (a) and (b):

(a) the inclination angle θ 2 t is greater than the inclination angle θ 2 c;

(b) the inclination angle θ 2 h is greater than the inclination angle θ 2 c.

3. The golf club according to claim 1 , wherein a trailing edge which is a rear edge of the trailing surface is curved so as to project toward the face side.

4. The golf club according to claim 1 , wherein a width of the trailing surface is greater than a width of the leading surface at all positions in a toe-heel direction.

5. The golf club according to claim 1 , wherein the head is an iron type head.

6. A golf club set constituted by the golf clubs according to claim 1 , and comprising the two or more golf clubs having different loft angles,

the golf club set satisfies at least one of the following (c) and (d):

(c) the inclination angle θ 2 t is increased as the loft angle is increased;

(d) the inclination angle θ 2 h is increased as the loft angle is increased.

7. The golf club set according to claim 6 , wherein the golf club set satisfies both the following (c) and (d):

(c) the inclination angle θ 2 t is increased as the loft angle is increased;

(d) the inclination angle θ 2 h is increased as the loft angle is increased.

8. The golf club set according to claim 6 , wherein the inclination angle θ 2 c is increased as the loft angle is increased.

9. The golf club set according to claim 6 , wherein if an inclination angle of the leading surface is defined as θ 1 ; the inclination angle θ 1 at the central position is defined as θ 1 c ; the inclination angle θ 1 at the toe reference position is defined as θ 1 t ; and the inclination angle θ 1 at the heel reference position is defined as θ 1 h,

the angle θ 1 t is increased as the loft angle is increased;

the angle θ 1 c is increased as the loft angle is increased; and

the angle θ 1 h is increased as the loft angle is increased.

10. A golf club set constituted by the golf clubs according to claim 1 and comprising the two or more golf clubs having different loft angles,

wherein if a difference (θ 2 t −θ 2 c ) between the inclination angle θ 2 t and the inclination angle θ 2 c is defined as a toe angle difference, and a difference (θ 2 h −θ 2 c ) between the inclination angle θ 2 h and the inclination angle θ 2 c is defined as a heel angle difference, the golf club set satisfies at least one of the following (e) and (f):

(e) the toe angle difference is increased as the loft angle is increased;

(f) the heel angle difference is increased as the loft angle is increased.

11. The golf club set according to claim 10 , wherein the golf club set satisfies both the following (e) and (f):

(e) the toe angle difference is increased as the loft angle is increased;

(f) the heel angle difference is increased as the loft angle is increased.