Even before he had engaged the Blood king, Sato already knew that he wasn't its match in direct combat. If he had a team or even a partner, then things would have been a lot more easier. Sadly, the Main trials seemed to be a solo-based challenge.
So, if Sato couldn't face it, then how was he supposed to defeat it?
The answer laid in Sato's setup.
'First one!'
When Sato was 75 metres away from the other end of the hall, which also happened to be where he came in from, he suddenly swung his sword out and pointed it at a certain spot in the hall. His movements seemed silly as even after 2 seconds, nothing happened.
However, as the Blood king passed the same place Sato pointed at, a brilliant orange light gleamed from the spot and exploded towards the Blood king. There wasn't just one flash but 4 from the four cardinal directions. One from each side which included in front and behind of the monster.