[shmaster]

I raged when the anime made the truck driving worthless. I have feared that this would happen ever since I read it off the manga.
The same goes to that Byakko, it felt ridiculous. Unless this really is a new game +. But that still doesn't justify the truck driving being worthless.

I'll explain the exact mechanic behind Dubhe's power while I am at it.

Spoiler for Dubhe:

Dubhe's power is total invincibility. Nothing can hurt it outside itself. (In game, it nulls every single type of attacks even the All Mighty ones)
Which is why I say the whole Byakko thing is ridiculous. Adding one mroe demon is pointless before Dubhe's invincibility trick.

What Daichi did is to luckily drop the truck onto Dubhe when the Dubhe is about to release the explosion.
To prevent the explosion from hurting itself, Dubhe always create the same amount of energy within itself for protection as the explosion when the explosion goes off.
But with that lucky ending of the truck, the energy on the outside and inside of Dubhe becomes unequal and thus Dubhe end up hruting itself with the explosion, shattering his invincibility.