I'm leaving this strat here because i cannot record it due to technical problems with my PC. But i got the time almost 30 seconds below the Manga% WR, so if anyone wants to try this out, go for it. (If anyone wants to know, i got 11:24 PB on manga%, but a bold claim is nothing without proof.)
I've noticed that the game deals with 2 types of damage, and the red one is the most important one, since it doesn't allow the opponent to do a long recover (the 8 seconds timer) while recovering all the damage. And it seems that blows on the body (Down+Attack/Special) are optimal for that.
The strat is basically, try to get the first dodge using the neutral one and go for Jab > Jab > Down Attack and then into a Down Special. ALTHOUGH for Miyata and Hayami you only have the first Special (Long Upper), which is not great, but it will do the job.
Detailed Explanation:
The sequence with Miyata is: Left Attack Combo WITHOUT Specials Until he KO's twice, then at the last KO you use the Up Special after one Left Combo. For Hayami is the same, but you only do it once since the needs to get KOed only 2 times.
Now you Unlocked Liver Blow, this is where the fun stuff happens.
Now everyone is the same strat: Jab > Jab > Down Attack > Down Special(Liver Blow), until they are KO. The last KO's, you will only need a simple combo to KO them.
Why this works better? Imo and my tests, if you do it right, the first KO will cost 9 second on the Timer for the opponent to recover, but it will be a fast KO overall, then he will use Get Up and Down Avoid, which idk how to avoid that but, he will be damaged enough for you to KO him even faster. So you will only lose a couple seconds at the start of the fight while the end of it will be fast.
Well, Good Luck for you all.
Notes: I think that the faster strat is some consistent thing to make the opponent waste all the Spirit (maybe with the guard cross or just his own specials), then you do this down combo strat, since it would lead to an instant KO. But i really don't have anything in mind for that since idk about the AI. It would be great if more ppl tried to run this game and find more stuff in it.