The game has 32 stages arranged in 8 different locations, 4 each.
Smaller enemies won't shoot during the 4th stage in each place.
Spoiler
MIDWAY
Stage 1 (Last 32)
Stage 2 (Last 31)
Stage 3 (Last 30)
Stage 4 (Last 29) - Bonus stage
MARSHALL
Stage 5 (Last 28)
Stage 6 (Last 27) - Extra life
Stage 7 (Last 26) - 1ST BOSS
Stage 8 (Last 25) - Bonus stage
ATTU
Stage 9 (Last 24)
Stage 10 (Last 23)
Stage 11 (Last 22)
Stage 12 (Last 21) - Bonus stage
RABAUL
Stage 13 (Last 20) - Extra life
Stage 14 (Last 19)
Stage 15 (Last 18) - 2ND BOSS
Stage 16 (Last 17) - Bonus stage
LEYTE
Stage 17 (Last 16)
Stage 18 (Last 15) - Extra life
Stage 19 (Last 14)
Stage 20 (Last 13) - Bonus stage
SAIPAN
Stage 21 (Last 12)
Stage 22 (Last 11)
Stage 23 (Last 10) - 3RD BOSS
Stage 24 (Last 09) - Bonus stage
IWOJIMA
Stage 25 (Last 08) - Extra life
Stage 26 (Last 07)
Stage 27 (Last 06)
Stage 28 (Last 05) - Bonus stage
OKINAWA
Stage 29 (Last 04) - Extra life
Stage 30 (Last 03)
Stage 31 (Last 02) - LAST BOSS (potential milking)
Stage 32 (Last Stage) - Bonus stage
Stage 1 (Last 32)
Stage 2 (Last 31)
Stage 3 (Last 30)
Stage 4 (Last 29) - Bonus stage
MARSHALL
Stage 5 (Last 28)
Stage 6 (Last 27) - Extra life
Stage 7 (Last 26) - 1ST BOSS
Stage 8 (Last 25) - Bonus stage
ATTU
Stage 9 (Last 24)
Stage 10 (Last 23)
Stage 11 (Last 22)
Stage 12 (Last 21) - Bonus stage
RABAUL
Stage 13 (Last 20) - Extra life
Stage 14 (Last 19)
Stage 15 (Last 18) - 2ND BOSS
Stage 16 (Last 17) - Bonus stage
LEYTE
Stage 17 (Last 16)
Stage 18 (Last 15) - Extra life
Stage 19 (Last 14)
Stage 20 (Last 13) - Bonus stage
SAIPAN
Stage 21 (Last 12)
Stage 22 (Last 11)
Stage 23 (Last 10) - 3RD BOSS
Stage 24 (Last 09) - Bonus stage
IWOJIMA
Stage 25 (Last 08) - Extra life
Stage 26 (Last 07)
Stage 27 (Last 06)
Stage 28 (Last 05) - Bonus stage
OKINAWA
Stage 29 (Last 04) - Extra life
Stage 30 (Last 03)
Stage 31 (Last 02) - LAST BOSS (potential milking)
Stage 32 (Last Stage) - Bonus stage
[Text/outline]
Green/black POW: Powers up the main weapon.
White/red POW: Destroys all enemies on screen.
Grey/orange POW: Adds the Side Fighters.
Black/red POW: Extra life.
Orange/black POW: Enemies become unable to shoot for a limited time.
Yellow/black POW: Increases the number of loops for the current stage.
Red/green POW: 1000 points.
Yashichi: 5000 points.
EXTRA LIVES:
There are 5 extra lives in this game. They're fixed (every POW is) and always granted by a specific formation at the beginning of certain stages (last 27, 20, 15, 8 & 4)
It's easy to miss one or two red enemies here so it's best to know when to be ready (especially after 1M points since the game stops giving extends).
SCORING:
Scoring comes from chaining large planes without dying (2000-9000 each), destroying medium-sized enemies, getting Yashichis and POWs, destruction% at the end of each level, 10M at the end of the game... and checkpoint milking performing a double KO in the last boss. You could do this up to 20 times for ~1.5M if you manage to clear the whole game, have enough lives remaining and decide to spend even more time on the run checkpoint-milking.