[okayama]

1st scramble: D' F U' F2 U R' B' R L' U R2 B' D2 R2 F2 R2 F' D2 F L2
1st solution (1-hour): B' L R' F' R2 B L B' R2 B L' U B' R B R B' R B2 R' U2 B2 U' D2 F' D (26 moves)

Spoiler (Click to View)

NISS solve.

(Inverse)
Pre-scramble: U' F R L' B

2x2x2 block: D' F D2
2x2x3 block: U B2 U2

(Normal)
Pre-scramble: U2 B2 U' D2 F' D

2x2x3 block: B' L R' F' * B U
F2L minus 1 slot: B' R B R
All but 3 corners: B' R B2 R'
Correction: U2 B2 U' D2 F' D

Insert at *: R2 B L B' R2 B L' B'

2nd scramble: U F2 U F2 R2 U2 B2 D' R2 U2 L U' B2 L' B' R' U' B U R2 F'
2nd solution (1-hour): F R' B' D B D' B' L B L' B' L D2 L D2 L U' L D' L' U L D U2 R' F2 U R' B2 (29 moves)

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30 min backup solution.

(Inverse)
Pre-scramble: R F'

2x2x1 block: B2 R
2x2x2 block: U' F2 R U2 *
2x2x3 block: L2 D2 L' D2 L'
Tripod: B L B' L' B
All but 3 corners: D B' D' B
Correction: R F'

Insert at *: D' L' U' L D L' U L

There were some other starts, for example L B2 R, or

B2 R U' F2 R U2 L' U B' U' D,

and so on, but no better solution was found in time.

3rd scramble: F D2 F' L2 U2 B2 R2 F' D2 B' U' L D2 R U' F' L U F
3rd solution (1-hour): R D L' U2 L U2 L' U L U' L' R' U' R U' R' U2 R U B' U2 L' U' L' D B D B' (28 moves)

Spoiler (Click to View)

NISS solve.

(Inverse)
Pre-scramble: L D' R'

2x2x2 block: B D' B' D'
More square: L U
More square: L
F2L minus 1 slot: U2 B

(Normal)
Pre-scramble: B' U2 L' U' L' D B D B'

F2L minus 1 slot: R D L'
Finish F2L: U2 L U2 L' U L U' L'
LL: R' U' R U' R' U2 R U
Correction: B' U2 L' U' L' D B D B'