The Sun Moon Empire's achievements in Soul Tools were closely tied to the generally low quality of its Martial Souls.
When the two continents collided thousands of years ago, its advantage in Soul Tools had given it a brief edge in the war, but it had ultimately lost to superior high-level fighters.
Under pressure from the three nations of the Douluo Continent, the empire, whose people generally had lower-quality Martial Souls, had been forced to devote the strength of the entire nation to Soul Tool research. Cultivation of Martial Souls had fallen further and further behind.
After the continents collided, however, the movement of people, Martial Soul Mutations, and the influence of the laws of heaven and earth had gradually brought high-quality and even top-tier Martial Souls into the Sun Moon Empire.
The ten people Sun Moon Academy had sent to Shrek on exchange ranked among the Empire's best in both talent and strength. Not one of them had an ordinary Martial Soul.
Soul Engineers from the Sun Moon Empire were constantly mocked as medicine jars by the Soul Master World, and they knew the accusation was true.
The drugs they gave most people to raise their cultivation did indeed draw on their potential and even their Life Force in advance, granting them power ahead of time.
Precisely because they understood the drawbacks, the truly strong were extremely cautious about using such drugs.
Those who dared to take them without a second thought were usually Soul Masters with low Innate Soul Power and poor-quality Martial Souls.
If they refused the bitter medicine, they would have to swallow the bitterness of life instead.
Rather than spend their lives stuck at an awkward level of cultivation, unable to advance an inch, they preferred to spend some Life Force to improve their lot.