[okayama]

1st scramble: F' R2 F' R2 F' R2 D2 L2 B D2 B R' D' L2 D2 L F' U' B2 D B
1st solution (1-hour): U B' F R2 F' U B' U F U' B F' U2 F L U' R U L' U' L' U' R2 L2 D' B R2 (27 moves)

Spoiler (Click to View)

(Inverse)
Pre-scramble: R2 F' B U'

Two squares: R2 B'
F2L minus 1 slot: D L2 R2 U L R' *
More c/e pairs: U F' U2 F
All but 3 corners: B' U F' U' B U' F
Correction: R2 F' B U'

Insert at *: R U L U' R' U L' U'

After the F2L minus 1 slot, the following continuation

U F' U L2 U' B' U B L2 F

leaves 3 corners with shorter moves (22), but it doesn't give a better result.

2nd scramble: U' B' D R2 L2 F B2 U2 R U2 D2 B' U2 F2 L2 F' L2 D2 F'
2nd solution (1-hour): R2 B U2 D B L' B' L D' B' U' B D B' U2 B D' B2 R' U' R2 U' B' F' L2 D' R U (28 moves)

Spoiler (Click to View)

30 min backup solution.

(Inverse)
Pre-scramble: U2 B' R2

2x2x1 block: U' R' D
2x2x2 block: L2 F
2x2x3 block: B U R'
F2L minus 1 slot: R' U R B * U'
All but 3 corners: B D L' B L B' D'
Correction: U2 B' R2

Insert at *: B D B' U2 B D' B' U2

Looks a nice scramble, there are some obvious starts on normal, such as

[1] U R2 F D2
[2] U2 R2 F' D2

but no better solution was found.

3rd scramble: R2 L2 F' L D L' B2 D' B' R' U2 B2 U2 B2 R2 D F2 L2 F2 R2 U'
3rd solution (1-hour): R B' L2 B L' R' B' D' B D R L' D L2 R D F' L B' L' F' L B L' D2 R' B F R2 (29 moves)

Spoiler (Click to View)

(Inverse)
Pre-scramble: L B' L2 B R'

1x2x2 block: R2 F'
1x2x3 block: B' R D
More square: D * F2 D'
Finish F2L: R' L2 D' L
All but 3 corners: R' D' B' D B R
Correction: L B' L2 B R'

Insert at *: L B' L' F L B L' F' (only 1-move cancels...)